Expanding cells in a bioreactor

ABSTRACT

Described are embodiments for expanding cells in a bioreactor. In one embodiment, methods are provided that distribute cells throughout the bioreactor and attach cells to specific portions of a bioreactor to improve the expansion of the cells in the bioreactor. Embodiments may be implemented on a cell expansion system configured to load, distribute, attach and expand cells.

CROSS-REFERENCE TO RELATED PATENT APPLICATION(S)

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/905,182 filed Nov. 16, 2013, entitled METHOD OF LOADING ANDDISTRIBUTING CELLS IN A BIOREACTOR OF A CELL EXPANSION SYSTEM, which ishereby incorporated by reference in its entirety as if set forth hereinin full.

BACKGROUND

The potential use of stem cells in a variety of treatments and therapieshas achieved particular attention. Cell expansion systems can be used toexpand, e.g., grow, stem cells, as well as other types of cells, such asbone marrow cells. Stem cells which are expanded from donor cells can beused to repair or replace damaged or defective tissues and have broadclinical applications for a wide range of diseases. Recent advances inthe regenerative medicine field demonstrates that stem cells haveproperties such as proliferation and self-renewal capacity, maintenanceof the unspecialized state, and the ability to differentiate intospecialized cells under particular conditions.

Cell expansion systems include one or more compartments for expandingthe cells, such as a cell growth chamber, also referred to herein as a“bioreactor.” In order to expand cells, an initial volume of cells istypically loaded into, and distributed within, the bioreactor.Accordingly, there is a need for a method of loading and distributingcells in a bioreactor associated with a cell expansion system. Thepresent disclosure addresses this and other needs.

Embodiments of the present invention have been made in light of theseand other considerations. However, the relatively specific problemsdiscussed above do not limit the applicability of the embodiments of thepresent invention to solving other problems.

SUMMARY

The summary is provided to introduce aspects of some embodiments of thepresent invention in a simplified form, and is not intended to identifykey or essential elements of the claimed invention, nor is it intendedto limit the scope of the claims.

It is to be understood that the present invention may include a varietyof different versions or embodiments, and this Summary is not meant tobe limiting or all-inclusive. This Summary provides some generaldescriptions of features that may be included in embodiments, and alsoinclude some more specific descriptions of other features that may beincluded in other embodiments.

One or more embodiments are generally directed to a method and systemfor loading and distributing cells in a bioreactor of a cell expansionsystem. Accordingly, embodiments include methods that may provide foradding a plurality of cells to a fluid circulating at a first ratewithin a bioreactor of the cell expansion system. In embodiments, thebioreactor may include a hollow fiber membrane with a plurality ofindividual hollow fibers through which the cells and other fluids arecirculated. Initially, fluid is circulated through the hollow fibermembrane of the bioreactor and cells are added to the circulating fluid.The fluid is circulated at a first predetermined circulation rate.During circulation, the bioreactor may be in a horizontal position.After the cells are loaded by being added to the circulation fluid, thecells may be allowed to circulate and distribute evenly throughout thesystem, with cells flowing into and out of the hollow fibers of thehollow fiber membrane. The circulation may then be stopped. The cellsare then allowed to settle, under the influence of gravity, and attachedto a first portion of the hollow fibers in the bioreactor. Inembodiments, the cells may be allowed to settle for a firstpredetermined period of time. In some embodiments, the predeterminedperiod of time may be selected to allow the cells also to attach to thefirst portion of the hollow fibers.

After the first predetermined period of time, the bioreactor is rotated180 degrees. After rotation of the bioreactor, cells within thebioreactor are allowed to settle again. Cells may then settle on anopposing portion of the hollow fibers for a second predetermined periodof time that may be selected to also allow the cells to attach to theopposing portion. After the second predetermined period of time, thebioreactor is rotated back to its original horizontal position and thecells undergo an expansion process.

In some embodiments, the loading process includes additional steps. Insome embodiments, after the bioreactor is returned to its originalhorizontal position, circulation is restarted. The circulation rate maybe set at a lower rate than the first predetermined circulation rate.The circulation would be performed to once again distribute cells thathave not attached to a surface. The circulation would continue for athird predetermined period of time to allow unattached cell to becomeevenly distributed throughout the system including the bioreactor. Thecirculation would then be stopped allowing cells in the bioreactor tosettle, and in embodiments attach to portions of the hollow fibers, onceagain.

After a fourth predetermined period of time to allow the cells to settleagain, the bioreactor is rotated 180 degrees. After rotation of thebioreactor, cells within the bioreactor are allowed to settle again.Cells may then settle on an opposing portion of the hollow fibers for afifth predetermined period of time that may be selected to also allowthe cells to attach to the opposing portion of the hollow fibers. Afterthe fifth predetermined period of time, the bioreactor is rotated backto its original horizontal position.

The process is again repeated by circulating cells in the system toevenly distribute any unattached cells, again. However, each timecirculation is restarted, it is restarted at a lower rate than theprevious circulation. When the circulation is stopped, the cells areallowed to settle and attach. The bioreactor is rotated 180 degrees andthe cells are allowed to settle and attach. Then the bioreactor isrotated back to its original position. These steps of circulation,settling, rotation, settling, and rotation may be repeated apredetermined number of times, after which the attached cells, whichhave been attached in layers, are expanded in the bioreactor.

Other embodiments are also directed to a method and system for loadingand distributing cells in a bioreactor of a cell expansion system.Embodiments include methods that may provide for adding a plurality ofcells to a fluid circulating at a first rate within a bioreactor of thecell expansion system. In embodiments, the bioreactor may include ahollow fiber membrane with a plurality of individual hollow fibersthrough which the cells and other fluids are circulated. Initially,fluid is circulated through the hollow fiber membrane of the bioreactorand cells are added to the circulating fluid. The fluid is circulated ata first predetermined circulation rate. During circulation, thebioreactor may be in a horizontal position. After the cells are loadedby being added to the circulation fluid, the cells may be allowed tocirculate and distribute evenly throughout the system, with cellsflowing into and out of the hollow fibers of the hollow fiber membrane.The circulation may then be stopped. The cells are then allowed tosettle, under the influence of gravity, and attached to a first portionof the hollow fibers in the bioreactor. In embodiments, the cells may beallowed to settle for a first predetermined period of time. In someembodiments, the predetermined period of time may be selected to allowthe cells also to attach to the first portion of the hollow fibers.

After the first predetermined period of time, the bioreactor is rotated180 degrees. After rotation of the bioreactor, the cells undergo anexpansion process. As may be appreciated, the previously attached cellsmay be on a top portion of the hollow fibers. As the cells are expanded,they may be subjected to gravity, which may influence cell growth towarda bottom portion of the hollow fibers.

Additional advantages of the embodiments presented herein will becomereadily apparent from the following discussion, particularly when takentogether with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1A depicts one embodiment of a cell expansion system (CES).

FIG. 1B depicts a second embodiment of a CES.

FIG. 1C depicts a third embodiment of a CES.

FIG. 1D depicts an embodiment of a rocking device for moving a cellgrowth chamber rotationally or laterally during operation of the CES.

FIG. 2A depicts a side view of an embodiment of a hollow fiber cellgrowth chamber.

FIG. 2B depicts a cut-away side view of the embodiment of the hollowfiber cell growth chamber illustrated in FIG. 2A.

FIG. 3 depicts a cut-away side view of another embodiment of abioreactor showing circulation paths through the bioreactor.

FIG. 4 illustrates a perspective view of a portion of a CES, including adetachably attached bioreactor, according to an embodiment.

FIG. 5 illustrates a flow chart of a method for expanding cells in a CESaccording to an embodiment.

FIG. 6 illustrates a flow chart of a process for loading, distributing,attaching, and expanding cells that includes steps that may be used inthe method of the flow chart illustrated in FIG. 5 in some embodiments.

FIG. 7 is a flow chart of a process for loading, distributing,attaching, and expanding cells that includes steps that may be used inthe method of the flow chart illustrated in FIG. 5 in some embodiments.

FIG. 8 illustrates a front elevation view of an embodiment of abioreactor in a first orientation.

FIG. 9 illustrates a front elevation view of the bioreactor of FIG. 8,wherein the bioreactor is shown rotated about 90 degrees from the viewof FIG. 8.

FIG. 10 is a front elevation view of the bioreactor of FIG. 8, whereinthe bioreactor is shown rotated about 180 degrees from the view of FIG.8

FIG. 11 is a front elevation view of the bioreactor of FIG. 8, whereinthe bioreactor is shown rotated back to the original orientation shownin FIG. 8.

FIG. 12 illustrates a front elevation view of the bioreactor of FIG. 8,wherein the bioreactor is shown rotated about 90 degrees from the viewof FIG. 8 and about 180 degrees from the view of FIG. 9.

FIGS. 13A-13C illustrate a cross section (perpendicular to a centralaxis) of a hollow fiber that may be part of a bioreactor as itprogresses through steps of a process for distributing, attaching, andexpanding cells in the bioreactor according to an embodiment.

FIGS. 13D and 13E illustrate a cross section (parallel to a centralaxis) of a hollow fiber that may be part of a bioreactor as itprogresses through steps of a process for expanding cells in thebioreactor according to an embodiment.

FIGS. 14A-14D illustrate a cross section (perpendicular to a centralaxis) of a hollow fiber that may be part of a bioreactor as itprogresses through steps of a process for distributing, attaching, andexpanding cells in the bioreactor according to another embodiment.

FIG. 15A-15F illustrate a cross section (perpendicular to a centralaxis) of a hollow fiber that may be part of a bioreactor as itprogresses through steps of a process for distributing attaching andexpanding cells in the bioreactor according to yet another embodiment.

FIG. 16 illustrates a cross section of a bioreactor showing a pluralityof hollow fibers and zones of hollow fibers through which liquidcontaining cells may circulate at different flow rates.

FIG. 17 illustrates a block diagram of a basic computer that may be usedto implement embodiments.

DETAILED DESCRIPTION

The principles of the present invention may be further understood byreference to the following detailed description and the embodimentsdepicted in the accompanying drawings. It should be understood thatalthough specific features are shown and described below with respect todetailed embodiments, the present invention is not limited to theembodiments described below. The present disclosure is generallydirected to a method for distributing a plurality of cells in abioreactor of a cell expansion system. As described below, a method ofdistributing cells within a bioreactor may include loading cells intothe bioreactor, rotating the bioreactor, and holding the bioreactorstill at certain orientations.

A schematic of an example cell expansion system (CES) is depicted inFIG. 1A. CES 10 includes first fluid circulation path 12 and secondfluid circulation path 14. First fluid flow path 16 has at leastopposing ends 18 and 20 fluidly associated with a hollow fiber cellgrowth chamber 24 (also referred to herein as a “bioreactor”).Specifically, opposing end 18 is fluidly associated with a first inlet22 of cell growth chamber 24, and opposing end 20 is fluidly associatedwith first outlet 28 of cell growth chamber 24. Fluid in firstcirculation path 12 flows through the interior of hollow fibers ofhollow fiber membrane disposed in cell growth chamber 24 (cell growthchambers and hollow fiber membranes are described in more detail infra).Further, first fluid flow controller 30 is operably connected to firstfluid flow path 16, and controls the flow of fluid in first circulationpath 12.

Second fluid circulation path 14 includes second fluid flow path 34,cell growth chamber 24, and a second fluid flow controller 32. Thesecond fluid flow path 34 has at least opposing ends 36 and 38. Opposingends 36 and 38 of second fluid flow path 34 are fluidly associated withinlet port 40 and outlet port 42 respectively of cell growth chamber 24.Fluid flowing through cell growth chamber 24 is in contact with theoutside of hollow fiber membrane in the cell growth chamber 24. Secondfluid circulation path 14 is operably connected to second fluid flowcontroller 32.

First and second fluid circulation paths 12 and 14 are thus separated incell growth chamber 24 by a hollow fiber membrane. Fluid in first fluidcirculation path 12 flows through the intracapillary (“IC”) space of thehollow fibers in the cell growth chamber. First circulation path 12 isthus referred to as the “IC loop.” Fluid in second circulation path 14flows through the extracapillary (“EC”) space in the cell growthchamber. Second fluid circulation path 14 is thus referred to as the “ECloop.” Fluid in first fluid circulation path 12 can flow in either aco-current or counter-current direction with respect to flow of fluid insecond fluid circulation path 14.

Fluid inlet path 44 is fluidly associated with first fluid circulationpath 12. Fluid inlet path 44 allows fluid into first fluid circulationpath 12, while fluid outlet path 46 allows fluid to leave CES 10. Thirdfluid flow controller 48 is operably associated with fluid inlet path44. Alternatively, third fluid flow controller 48 can alternatively beassociated with fluid outlet path 46.

Fluid flow controllers as used herein can be a pump, valve, clamp, orcombination thereof. Multiple pumps, valves, and clamps can be arrangedin any combination. In various embodiments, the fluid flow controller isor includes a peristaltic pump. In further embodiments, fluidcirculation paths, inlet ports, and outlet ports can be constructed oftubing of any material.

Various components are referred to herein as “operably associated.” Asused herein, “operably associated” refers to components that are linkedtogether in operable fashion, and encompasses embodiments in whichcomponents are linked directly, as well as embodiments in whichadditional components are placed between the two linked components.“Operably associated” components can be “fluidly associated.” “Fluidlyassociated” refers to components that are linked together such thatfluid can be transported between them. “Fluidly associated” encompassesembodiments in which additional components are disposed between the twofluidly associated components, as well as components that are directlyconnected. Fluidly associated components can include components that donot contact fluid, but contact other components to manipulate the system(e.g. a peristaltic pump that pumps fluids through flexible tubing bycompressing the exterior of the tube).

Generally, any kind of fluid, including buffers, protein containingfluid, and cell-containing fluid can flow through the variouscirculations paths, inlet paths, and outlet paths. As used herein,“fluid,” “media,” and “fluid media” are used interchangeably.

FIG. 1B depicts a more detailed cell expansion system 800. CES 800includes a first fluid circulation path 802 (also referred to as the“intracapillary loop” or “IC loop”) and second fluid circulation path804 (also referred to as the “extracapillary loop” or “EC loop”). Firstfluid flow path 806 is fluidly associated with cell growth chamber 801through fluid circulation path 802. Fluid flows into cell growth chamber801 through IC inlet port 801A, through hollow fibers in cell growthchamber 801, and exits via IC outlet port 801B. Pressure sensor 810measures the pressure of media leaving cell growth chamber 801. Inaddition to pressure, sensor 810 may in embodiments also be atemperature sensor that detects the media pressure and temperatureduring operation. Media flows through IC circulation pump 812 which canbe used to control the rate of media flow, e.g., circulation rate in theIC loop. IC circulation pump 812 may pump the fluid in a first directionor second direction opposite the first direction. Exit port 801B can beused as an inlet in the reverse direction. Media entering the IC loop802 may enter through valve 814. As those skilled in the art willappreciate, additional valves and/or other devices can be placed atvarious locations to isolate and/or measure characteristics of the mediaalong portions of the fluid paths. Accordingly, it is to be understoodthat the schematic shown represents one possible configuration forvarious elements of the CES 800 and modifications to the schematic shownare within the scope of the one or more present embodiments.

With regard to the IC loop 802, samples of media can be obtained fromsample coil 818 during operation. Media then returns to IC inlet port801A to complete fluid circulation path 802. Cells grown/expanded incell growth chamber 801 can be flushed out of cell growth chamber 801into harvest bag 899 through valve 898 and line 897. Alternatively, whenvalve 898 is closed, the cells may be redistributed, e.g., circulatedback, within chamber 801 for further growth or loading.

Fluid in second fluid circulation path 804 enters cell growth chamber801 via EC inlet port 801C, and leaves cell growth chamber 801 via ECoutlet port 801D. Media in the EC loop 804 is in contact with theoutside of the hollow fibers in the cell growth chamber 801, therebyallowing diffusion of small molecules into and out of the hollow fibersthat may be within chamber 801.

Pressure/temperature sensor 824 disposed in the second fluid circulationpath 804 allows the pressure and temperature of media to be measuredbefore the media enters the EC space of the cell growth chamber 801.Sensor 826 allows the pressure and temperature of media in the secondfluid circulation path 804 to be measured after it leaves the cellgrowth chamber 801. With regard to the EC loop 804, samples of media canbe obtained from sample port 830 or a sample coil during operation.

After leaving EC outlet port 801D of cell growth chamber 801, fluid insecond fluid circulation path 804 passes through EC circulation pump 828to gas transfer module 832. EC circulation pump 828 may also pump thefluid in opposing directions. Second fluid flow path 822 is fluidlyassociated with gas transfer module 832 via an inlet port 832A and anoutlet port 832B of gas transfer module 832. In operation, fluid mediaflows into gas transfer module 832 via inlet port 832A, and exits gastransfer module 832 via outlet port 832B. Gas transfer module 832 addsoxygen to and removes bubbles from media in the CES 800. In variousembodiments, media in second fluid circulation path 804 is inequilibrium with gas entering gas transfer module 832. The gas transfermodule 832 can be any appropriately sized device known in the art anduseful for oxygenation or gas transfer. Air or gas flows into gastransfer module 832 via filter 838 and out of oxygenator or gas transferdevice 832 through filter 840. Filters 838 and 840 reduce or preventcontamination of oxygenator 832 and associated media. Air or gas purgedfrom the CES 800 during portions of a priming sequence can vent to theatmosphere via the gas transfer module 832.

In the configuration depicted for CES 800, fluid media in first fluidcirculation path 802 and second fluid circulation path 804 flows throughcell growth chamber 801 in the same direction (a co-currentconfiguration). The CES 800 can also be configured to flow in acounter-current conformation.

In accordance with at least one embodiment, media, including cells (froma source such as a cell container, e.g. a bag) can be attached atattachment point 862, and fluid media from a media source can beattached at attachment point 846. The cells and media can be introducedinto first fluid circulation path 802 via first fluid flow path 806.Attachment point 862 is fluidly associated with the first fluid flowpath 806 via valve 864, and attachment point 846 is fluidly associatedwith the first fluid flow path 806 via valve 850. A reagent source maybe fluidly connected to point 844 and be associated with fluid inletpath 842 via valve 848, or second fluid inlet path 874 via valves 848and 872.

Air removal chamber (ARC) 856 is fluidly associated with firstcirculation path 802. The air removal chamber 856 may include one ormore sensors including an upper sensor and lower sensor to detect air, alack of fluid, and/or a gas/fluid interface, e.g., an air/fluidinterface, at certain measuring positions within the air removal chamber856. For example, ultrasonic sensors may be used near the bottom and/ornear the top of the air removal chamber 856 to detect air, fluid, and/oran air/fluid interface at these locations. Embodiments provide for theuse of numerous other types of sensors without departing from the spiritand scope of the present disclosure. For example, optical sensors may beused in accordance with embodiments of the present disclosure. Air orgas purged from the CES 800 during portions of the priming sequence orother protocols can vent to the atmosphere out air valve 860 via line858 that is fluidly associated with air removal chamber 856.

An EC media source may be attached to EC media attachment point 868 anda wash solution source may be attached to wash solution attachment point866, to add EC media and/or wash solution to either the first or secondfluid flow path. Attachment point 866 may be fluidly associated withvalve 870 that is fluidly associated with first fluid circulation path802 via valve 872 and first fluid inlet path 842. Alternatively,attachment point 866 can be fluidly associated with second fluidcirculation path 804 via second fluid inlet path 874 and EC inlet path884 by opening valve 870 and closing valve 872. Likewise, attachmentpoint 868 is fluidly associated with valve 876 that may be fluidlyassociated with first fluid circulation path 802 via first fluid inletpath 842 and valve 872. Alternatively, fluid container 868 may befluidly associated with second fluid inlet path 874 by opening valve 876and closing valve distribution 872.

In the IC loop 802, fluid may be initially advanced by the IC inlet pump854. In the EC loop 804, fluid is initially advanced by the EC inletpump 878. An air detector 880, such as an ultrasonic sensor, may also beassociated with the EC inlet path 884.

In at least one embodiment, first and second fluid circulation paths 802and 804 are connected to waste line 888. When valve 890 is opened, ICmedia can flow through waste line 888 and to waste bag 886. Likewise,when valve 892 is opened, EC media can flow to waste bag 886.

After cells have been grown in cell growth chamber 801, they may beharvested via cell harvest path 897. Here, cells from cell growthchamber 801 can be harvested by pumping the IC media containing thecells through cell harvest path 897, with valve 898 open, into cellharvest bag 899.

Various components of the CES 800 can be contained or housed within amachine or housing 899, such as cell expansion machine, wherein themachine maintains cells and media at a predetermined temperature. It isfurther noted that in embodiments, components of CES 800 may be combinedwith other CES's such as CES 10 (FIG. 1A) or CES 900 (FIG. 1C). In otherembodiments, a CES may include fewer components than shown in FIG. 1A-Cand still be within the scope of the present disclosure.

FIG. 1C depicts another embodiment of a CES. CES 900 includes firstfluid circulation path 902 (also referred to as the “intracapillary (IC)loop”) and second fluid circulation path 904 (also referred to as the“extracapillary loop” or “EC loop”).

First fluid flow path 906 is fluidly associated with cell growth chamber908 through first fluid circulation path 902. Fluid flows into cellgrowth chamber 908 through inlet port 910, through hollow fibers in cellgrowth chamber 908, and exits via outlet port 907. Pressure gauge 917measures the pressure of media leaving cell growth chamber 908. Mediaflows through valve 913 and pump 911, which can be used to control therate of media flow. Samples of media can be obtained from sample port905 or sample coil 909 during operation. Pressure/temperature gauge 915disposed in first fluid circulation path 902 allows detection of mediapressure and temperature during operation. Media then returns to inletport 910 to complete fluid circulation path 902. Cells expanded in cellgrowth chamber 908 can be flushed out of cell growth chamber 908 orredistributed within hollow fibers for further growth.

Second fluid circulation path 904 includes second fluid flow path 912that is fluidly associated with cell growth chamber 908 in a loop. Fluidin second fluid circulation path 904 enters cell growth chamber 908 viainlet port 914, and leaves cell growth chamber 908 via outlet port 916.Media is in contact with the outside of the hollow fibers in the cellgrowth chamber 908, allowing diffusion of small molecules into and outof the hollow fibers.

Pressure/temperature gauge 919 disposed in the second circulation path904 allows the pressure and temperature of media to be measured beforethe media enters the EC space of the cell growth chamber 908. Pressuregauge 921 allows the pressure of media in the second circulation path904 to be measured after it leases leaves the cell growth chamber 908.

After leaving outlet port 916 of cell growth chamber 908, fluid insecond fluid circulation path 904 passes through pump 920 and valve 922to oxygenator 918. Second fluid flow path 912 is fluidly associated withoxygenator 918 via oxygenator inlet port 924 and oxygenator outlet port926. In operation, fluid media flows into oxygenator 918 via oxygenatorinlet port 924, and exits oxygenator 918 via oxygenator outlet port 926.

Oxygenator 918 adds oxygen to media in the CES 900. In variousembodiments, media in second fluid circulation path 904 is inequilibrium with gas entering oxygenator 918. The oxygenator can be anyoxygenator known in the art. Gas flows into oxygenator 918 via filter928 and out of oxygenator 918 through filter 930. Filters 928 and 930reduce or prevent contamination of oxygenator 918 and associated media.

In the configuration depicted for CES 900, fluid media in firstcirculation path 902 and second circulation path 904 flow through cellgrowth chamber 908 in the same direction (a co-current configuration).Those of skill in the art will recognize that CES 900 can also beconfigured in a counter-current conformation. Those of skill in the artwill recognize that the respective inlet and outlet ports can bedisposed in the cell growth chamber 908 at any location.

Cells and fluid media can be introduced to fluid circulation path 902via first fluid inlet path 932. Fluid container 934 and fluid container936 are fluidly associated with first fluid inlet path 932 via valves938 and 940 respectively. Likewise, cell container 942 is fluidlyassociated with first fluid circulation path 902 via valve 943. Cellsand fluid may in some embodiments proceed through heat exchanger 944,pump 946, and into drip chamber 948. In embodiments where cells fromcontainer 942 are passed through heat exchanger 944, an additional line(not shown) would be used to connect container 942 to heat exchanger944. Drip chamber 948 is fluidly associated with first circulation path902. Overflow from drip chamber 948 can flow out of drip chamber 948from overflow line 950 via valve 952.

Additional fluid can be added to first or second fluid circulation paths902 and 904 from fluid container 954 and fluid container 956. Fluidcontainer 954 is fluidly associated with valve 958 which is fluidlyassociated with first fluid circulation path 902 via valve 964, patt960, and path 932. Alternatively, fluid container 954 is fluidlyassociated with second fluid inlet path 962. Likewise, fluid container956 is fluidly associated with valve 966, which is fluidly associatedwith first fluid circulation path 902 via first fluid inlet path 960.Alternatively, fluid container 956 is fluidly associated with secondfluid inlet path 962.

Second fluid inlet path 962 is configured to allow fluid to flow throughheat exchanger 944, pump 968, before entering drip chamber 970. Secondfluid inlet path 962 continues to second fluid circulation path 904.Overflow fluid can flow out via overflow line 972 through valve 974 towaste container 976.

Cells can be harvested via cell harvest path 978. Cells from cell growthchamber 908 can be harvested by pumping media containing the cellsthrough cell harvest path 978 to cell harvest bag 980, when valve 982 isopened.

First and second fluid circulation paths 902 and 904 are connected byconnector path 984. When valve 986 is opened, media can flow throughconnector path 984 between first and second circulation paths 902 and904. Likewise, pump 990 can pump media through another connector path988 between first and second fluid circulation paths 902 and 904.

Various components of the CES 900 can be contained within incubator 999.Incubator 999 maintains cells and media at a constant temperature.

As will be recognized by those of skill in the art, any number of fluidcontainers (e.g. media bags) can be fluidly associated with the CES 900in any combination. It will further be noted that the location of thedrip chamber 948, or sensors independent of the drip chamber 948, can beat any location in the CES 900 before inlet port 910.

CES's 800 and 900 can include additional components. For example, one ormore pump loops (not shown) can be added at the location of peristalticpumps on a CES. The pump loops may be made of polyurethane (PU)(available as Tygothane C-210A)). Alternatively, a cassette fororganizing the tubing lines and which may also contain tubing loops forthe peristaltic pumps may also be included as part of the disposable.

A detachable flow circuit (also referred to herein as a “detachablecirculation module”) may also be provided in some embodiments. Thedetachable flow circuit may be a portion of a cell expansion moduleconfigured to attach to a more permanent fixed portion of the CES.Generally, the fixed portions of the CES include peristaltic pumps. Invarious embodiments, the fixed portions of the CES can include valvesand/or clamps.

The detachable flow circuit can include a first fluid flow path havingat least two ends. The first end is configured to be fluidly associatedwith a first end of a cell growth chamber, and a second end of the firstfluid flow path configured to fluidly associated with a second end ofthe cell growth chamber.

Likewise, the detachable flow circuit can include a second fluid flowpath having at least two ends. Portions of the detachable flow circuitcan be configured to be fluidly associated with an oxygenator and/orbioreactor. The detachable flow circuit can include a second fluid flowpath that may be configured to fluidly associate with the oxygenator andcell growth chamber.

In various embodiments, the detachable flow circuit may be detachablyand disposably mounted to a fluid flow controller. The detachable flowcircuit can include detachable fluid conduits (e.g. flexible tubing)that connects portions of the CES.

In further embodiments, the detachable flow circuit can include a cellgrowth chamber, oxygenator, as well as bags for containing media andcells. In various embodiments, the components can be connected together,or separate. Alternatively, detachable flow circuit can include one ormore portions configured to attach to fluid flow controllers, such asvalves, pumps, and combinations thereof. In variations where peristalticpumps are used, the detachable circuit module can include a peristalticloop configured to fit around a peristaltic portion of the tubing. Invarious embodiments, the peristaltic loop can be configured to befluidly associated with the circulations paths, inlet paths, and outletpaths. The detachable flow circuit can be combined in a kit withinstructions for its assembly or attachments to fluid flow controllers,such as pumps and valves.

Embodiments provide for using a number of different methods to introducecells into bioreactors of CES. As described in greater detail below,embodiments include methods and systems that distribute cells in thebioreactor to promote consistent expansion of cells.

According to embodiments, cells can be grown (“expanded”) in either theIC loop or the EC loop. Adherent and non-adherent suspension cells canbe expanded. In one embodiment, the lumen of the cell growth chamberfibers can be coated with fibronectin. Divalent cation-free (e.g.calcium and magnesium-free) PBS is added to a CES system. After adherentcells are introduced into a cell growth chamber, e.g., chamber 24, 801,or 908 they are incubated for a sufficient time to adhere to the hollowfibers. IC and EC media are circulated to ensure sufficient nutrientsare supplied to the cells.

The flow rate of the IC loop and EC loop can be adjusted to a specificvalue. In various embodiments, the flow rate of the IC loop and EC loopscan be, independently set to, about 2, about 4, about 6, about 8, about10, about 15, about 20, about 25, about 30, about 35, about 40, about45, about 50, about 60, about 70, about 80, about 90, about 100, about200, about 300, about 400 or even about 500 mL/minute. In variousembodiments, the flow rates for the IC circuit loop may be set fromabout 10 to about 20 mL/minute, and the flow rate of the EC circuit loopmay be set from 20 to about 30 mL per minute (allowing media to flowthrough an oxygenator and re-establish oxygen levels). Additional mediamay be pumped into the CES at a lower flow rate (e.g. 0.1 mL per minutein some embodiments) to replace media that evaporates through a gasexchange module(s) such as gas exchange/oxygenators 832 and 918. Invarious embodiments, the EC loop removes cellular waste, and the IC loopincludes growth factors in the media.

CES's may provide a great deal of flexibility in varying growthconditions and criteria. Cells can be kept in suspension in the IC loopby circulating media continuously. Alternatively, media circulation canbe stopped, causing cells to settle. Fresh media can be added to the ICloop by ultrafiltration to accommodate excess volume without removingcells. EC media circulation allows for exchange of gas, nutrients, wasteproducts, and addition of new media without removing cells.

Expanded cells can include adherent cells, non-adherent cells, or aco-culture of any combination of cells in the art. Some non-limitingexamples of cells that maybe grown in a embodiments of a CES, include,without limitation, stem cells (e.g., mesenchymal, hematopoietic, etc.),fibroblasts, keratinocytes, progenitor cells, other fully differentiatedcells and combinations thereof.

In embodiments, to harvest adherent cells, the IC and EC media may bereplaced with media that is free of divalent cations (e.g. divalentcation-free PBS). In one embodiment, trypsin may be loaded into a firstcirculation path, and allowed to incubate with adherent cells for aperiod of time (in some embodiments about 5 to about 10 minutes). Thetrypsin may then be flushed from the system. A shearing force may beapplied to the cells by increasing the flow rate through cell growthchamber, and adherent cells that are released from the cell growthchamber may be pumped to a cell harvest bag.

When non-adherent cells are expanded, the cells can be flushed from thecirculating IC circuit. Adherent cells remain in the cell growthchamber, while non-adherent cells are removed.

The CES can be used to perform a variety of cell expansion methods. Inone embodiment, a seeded population of cells can be expanded. Cells areintroduced, or seeded, into the CES. In certain circumstances, the lumenof the hollow fibers can be conditioned to allow cell adhesion. Cellsare then added to the cell growth chamber, and adherent cells adhere tothe hollow fibers, while non-adherent cells (e.g. hematopoietic stemcells, or HSCs) do not adhere. The non-adherent cells can be flushedfrom the system. After incubation for a period of time, the adherentcells can be released and harvested.

The cell growth chamber of the cell expansion system in embodimentsincludes a hollow fiber membrane comprised of a plurality ofsemi-permeable hollow fibers separating first and second fluidcirculation paths.

The CES can include a device configured to move or “rock” the cellgrowth chamber relative to other components of the cell expansion systemby attaching it to a rotational and/or lateral rocking device. FIG. 1Dshows one such device, in which a bioreactor 400 is rotationallyconnected to two rotational rocking components, and a lateral rockingcomponent.

A first rotational rocking device component 402 rotates the bioreactor400 around central axis 410 of the bioreactor. Bioreactor 400 is alsoconnected to lateral rocking device 404. Rotational rocking devicecomponent 402 is rotationally associated to bioreactor 400. Therotational rocking device 402 then rotates bioreactor 400 around centralaxis 410 of the bioreactor. Rotation can occur in a clockwise orcounter-clockwise direction. Bioreactor 400 can be rotated continuouslyin a single direction around central axis 410 in a clockwise orcounterclockwise direction. Alternatively, bioreactor 400 can rotate inalternating fashion, first clockwise, then counterclockwise aroundcentral axis 410.

The CES can also include a second rotational rocking component thatrotates bioreactor 400 around rotational axis 412. Rotational axis 412passes through the center of point of bioreactor 400 and is normal tocentral axis 410. Bioreactor 400 can be rotated continuously in a singledirection around rotational axis 412 in a clockwise or counterclockwisedirection. Alternatively, bioreactor 400 can be rotated aroundrotational axis 412 in an alternating fashion, first clockwise, thencounterclockwise. In various embodiments, bioreactor 400 can also berotated around rotational axis 412 and positioned in a horizontal orvertical orientation relative to gravity.

Lateral rocking component 404 is laterally associated with bioreactor400. The plane of lateral rocking component 404 moves laterally in the−x and −y directions. The settling of cells in the bioreactor 400 isthereby reduced with the movement of cell-containing media within thehollow fibers.

The rotational and/or lateral movement of the rocking device can reducethe settling of cells within the device and reduce the likelihood ofcells becoming trapped within a portion of the bioreactor 400. The rateof cells settling in the cell growth chamber (e.g., bioreactor 400) isproportional to the density difference between the cells and thesuspension media according to Stoke's Law. In certain embodiments, a 180degree rotation (fast) with a pause (having a total combined time of 30seconds) repeated as described above keeps non-adherent red blood cellssuspended. A minimum rotation of about 180 degrees is performed in someembodiments; however, one could use rotation of up to 360 degrees orgreater in other embodiments. Different rocking components can be usedseparately, or can be combined in any combination. For example, arocking component that rotates bioreactor 400 around central axis 410can be combined with the rocking component that rotates bioreactor 400around axis 412. Likewise, clockwise and counterclockwise rotationaround different axes can be performed independently in any combination.

It is noted that the rocking devices, and their components, describedabove, may be implemented in embodiments using any appropriatestructure. For example, in embodiments, one or more motors may be usedas rocking devices, or components (e.g. 402 and 404) of rocking devices.In one embodiment, the rocking devices may be implemented usingembodiments shown and described in U.S. Pat. No. 8,399,245 entitledROTATION SYSTEM FOR CELL GROWTH CHAMBER OF A CELL EXPANSION SYSTEM ANDMETHOD OF USE THEREFOR, issued Mar. 19, 2013, which is herebyincorporated by reference in its entirety as if set forth herein infull.

An embodiment of a cell growth chamber is depicted in FIGS. 2B and 2A,which depicts a cut-away and side view of a hollow fiber cell growthchamber 200, which may be referred to as a “bioreactor.” Cell growthchamber 200 is bounded by cell growth chamber housing 202. Cell growthchamber housing 202 further includes four openings, or ports: inlet port204, outlet port 206, inlet port 208, and outlet port 210.

Fluid in the first circulation path enters cell growth chamber 200through inlet port 204, passes into and through the intracapillary sideof a plurality of hollow fibers 212 (referred to in various embodimentsas the intracapillary (“IC”) side or “IC space” of a hollow fibermembrane), and out of cell growth chamber 200 through outlet port 206.The terms “hollow fiber,” “hollow fiber capillary,” and “capillary” areused interchangeably. A plurality of hollow fibers 212 are collectivelyreferred to as a “membrane.” Fluid in the second circulation path flowsin the cell growth chamber through inlet port 208, comes in contact withthe outside of the hollow fibers 212 (referred to as the “EC side” or“EC space” of the membrane), and exits cell growth chamber 200 viaoutlet port 210. Cells can be contained within the first circulationpath or second circulation path, and can be on either the IC side or ECside of the membrane.

Although cell growth chamber housing 202 is depicted as cylindrical inshape, it can have any other shape known in the art. Cell growth chamberhousing 202 can be made of any type of biocompatible polymeric material.Various other cell growth chamber housings may differ in shape and size.

Those of skill in the art will recognize that the term cell growthchamber does not imply that all cells being grown or expanded in a CESare grown in the cell growth chamber. In many embodiments, adherentcells can adhere to membranes disposed in the growth chamber, or maygrow within the associated tubing. Non-adherent cells (also referred toas “suspension cells”) can also be grown. Cells can be grown in otherareas within the first or second fluid circulation path.

For example, the ends of hollow fibers 212 can be potted to the sides ofthe cell growth chamber 200 by a connective material (also referred toherein as “potting” or “potting material”). The potting can be anysuitable material for binding the hollow fibers 212, provided that theflow of media and cells into the hollow fibers is not obstructed andthat liquid flowing into the cell growth chamber 200 through the ICinlet port flows only into the hollow fibers 212. Exemplary pottingmaterials include, but are not limited to, polyurethane or othersuitable binding or adhesive components. In various embodiments, thehollow fibers 212 and potting may be cut through perpendicular to thecentral axis of the hollow fibers 212 at each end to permit fluid flowinto and out of the IC side. End caps 214 and 216 are disposed at theend of the cell growth chamber.

Fluid entering cell growth chamber 200 via inlet port 208 is in contactwith the outside of hollow fibers 212. This portion of the hollow fibercell growth chamber is referred to as the “extracapillary (EC) space.”Small molecules (e.g. water, oxygen, lactate, etc.) can diffuse throughthe hollow fibers 212 from the interior of the hollow fiber to the ECspace, or from the EC space to the IC space. Large molecular weightmolecules such as growth factors are typically too large to pass throughthe hollow fibers 212, and remain in the IC space of the hollow fibers.In embodiments in which cells are grown in the IC space, the EC space isused as a medium reservoir to supply nutrients to the cells and removethe byproducts of cellular metabolism. The media may be replaced asneeded. Media may also be circulated through an oxygenator to exchangegasses as needed.

In various embodiments, cells can be loaded into the hollow fibers 212by any of a variety of methods, including by syringe. The cells may alsobe introduced into the cell growth chamber 200 from a fluid container,such as a bag, which may be fluidly associated with the cell growthchamber.

Hollow fibers 212 are configured to allow cells to grow in theintracapillary space (i.e. inside the hollow fiber lumen) of the fibers.Hollow fibers 212 are large enough to allow cell adhesion in the lumenwithout substantially impeding the flow of media through the hollowfiber lumen. In various embodiments, the inner diameter of the hollowfiber can be greater than or equal to about 10000, about 9000, about8000, about 7000, about 6000, about 5000, about 4000, about 3000, about2000, about 1000, about 900, about 800, about 700, about 650, about 600,about 550, about 500, about 450, about 400, about 350, about 300, about250, about 200, about 150, or even about 100 microns. Likewise, theouter diameter of the hollow fiber can be less than or equal to about10000, about 9000, about 8000, about 7000, about 6000, about 5000, about4000, about 3000, about 2000, about 1000, about 900, about 800, about700, about 650, about 700, about 650, about 600, about 550, about 500,about 450, about 400, about 350, about 300, about 250, about 200, about150, or even about 100 microns. The hollow fiber wall thickness shouldbe sufficient to allow diffusion of small molecules, in someembodiments.

Any number of hollow fibers can be used in a cell growth chamber,provided the hollow fibers can be fluidly associated with the inlet andoutlet ports of the cell growth chamber. In various embodiments, thecell growth chamber can include a number of hollow fibers greater thanor equal to about 1000, about 2000, about 3000, about 4000, about 5000,about 6000, about 7000, about 8000, about 9000, about 10000, about 11000or about 12000. In other embodiments, the cell growth chamber caninclude a number of hollow fibers less than or equal to about 12000,about 11000, about 10000, about 9000, about 8000, about 7000, about6000, about 5000, about 4000, about 3000, or even about 2000. In othervarious embodiments, the length of the hollow fibers can be greater thanor equal to about 100, about 200, about 300, about 400, about 500, about600, about 700, about 800, or about 900 millimeters. In embodiments, thecell growth chamber contains about 9000 hollow fibers that have anaverage length of about 295 mm, an average inner diameter of 215microns, and an average outer diameter of about 315 microns.

Hollow fibers can be constructed of any material capable of forming asize sufficient to form fibers capable of transporting liquid from thecell growth chamber inlet port to the cell growth chamber outlet port.In various embodiments, the hollow fibers can be constructed fromplastic adherent materials capable of binding to certain types of cells,such as adherent stem cells (e.g. MSCs). In various other embodiments,hollow fibers can be treated with compounds such as fibronectin to formadherent surfaces.

In certain embodiments, the hollow fibers may be made of asemi-permeable, biocompatible polymeric material. One such polymericmaterial which can be used is a blend of polyamide, polyarylethersulfoneand polyvinylpyrrolidone (referred to herein as “PA/PAES/PVP”). Thesemi-permeable membrane allows transfer of nutrients, waste anddissolved gases through the membrane between the EC space and IC space.In various embodiments, the molecular transfer characteristics of thehollow fiber membranes are chosen to minimize loss of expensive reagentsnecessary for cell growth such as growth factors, cytokines etc. fromthe hollow fiber, while allowing metabolic waste products to diffusethrough the membrane into the hollow fiber lumen side to be removed.

In certain variations, one outer layer of each PA/PAES/PVP hollow fibermay be characterized by a homogenous and open pore structure with adefined surface roughness. The openings of the pores may be in the sizerange of about 0.5 to about 3 microns, and the number of pores on theouter surface of the fibers may be in the range of about 10,000 to about150,000 pores per mm². This outer layer has a thickness of about 1 toabout 10 microns. The next layer in each hollow fiber may be a secondlayer having the form of a sponge structure and, in embodiments have athickness of about 1 to about 15 microns. This second layer may serve asa support for the outer layer. A third layer next to the second layermay have the form of finger-like structures. This third layer providesmechanical stability and a high void volume which gives the membrane alow resistance to transporting molecules through the membrane. Duringuse, the finger-like voids are filled with fluid and the fluid gives alower resistance for diffusion and convection than a matrix with asponge-filled structure having a lower void volume. This third layer mayhave a thickness of about 20 to about 60 microns.

In further embodiments, the hollow fiber membrane can include betweenabout 65 to about 95% by weight of at least one hydrophobic polymer andbetween about 5 to about 35% by weight of at least one hydrophilicpolymer. The hydrophobic polymer may be chosen from the group consistingof polyamide (PA), polyaramide (PAA), polyarylethersulphone (PAES),polyethersulphone (PES), polysulphone (PSU), polyarylsulphone (PASU),polycarbonate (PC), polyether, polyurethane (PUR), polyetherimide andcopolymer mixtures of any of the above polymers, such aspolyethersulphone or a mix of polyarylethersulphone and polyamide. Inadditional embodiments, the hydrophilic polymer may be chosen from thegroup consisting of polyvinylpyrrolidone (PVP), polyethylene glycol(PEG), polyglycolmonoester, water soluble cellulosic derivates,polysorbate and polyethylene-polypropylene oxide copolymers.

Depending upon the type of cells to be expanded in the cell growthchamber, the polymeric fibers may be treated with a substance, such asfibronectin, to enhance cell growth and/or adherence of the cells to themembrane.

With reference now to FIG. 3, an example of another cell growth chamber,bioreactor 300, is shown in a cut-away side view. Bioreactor 300 has alongitudinal axis LA-LA and includes bioreactor housing 304. In at leastone embodiment, bioreactor housing 304 includes four openings or ports:IC inlet port 308, IC outlet port 320, EC inlet port 328, and EC outletport 332.

Fluid in a first circulation path enters bioreactor 300 through IC inletport 308 at a first longitudinal end 312 of the bioreactor 300, passesinto and through the intracapillary side (referred to in variousembodiments as the intracapillary (“IC”) side or “IC space” of a hollowfiber membrane) of a plurality of hollow fibers 316, and out ofbioreactor 300 through IC outlet port 320 located at a secondlongitudinal end 324 of the bioreactor 300. Fluid in a secondcirculation path flows in the bioreactor 300 through EC inlet port 328,comes in contact with the extracapillary side or outside (referred to asthe “EC side” or “EC space” of the membrane) of the hollow fibers 316,and exits bioreactor 300 via EC outlet port 332. Fluid enteringbioreactor via an EC inlet port 328 is in contact with the outside ofthe hollow fibers. Small molecules (e.g. water, oxygen, lactate, etc.)can diffuse through the hollow fibers from the interior of the hollowfiber to the EC space, or from the EC space to the IC space. Largemolecular weight molecules such as growth factors are typically toolarge to pass through the hollow fibers, and remain in the IC space ofthe hollow fibers. The media may be replaced as needed. Media may alsobe circulated through an oxygenator to exchange gasses as needed. Cellscan be contained within the first circulation path and/or secondcirculation path, and can be on either the IC side and/or EC side of themembrane. By way of example and not limitation, in one embodiment, thebioreactor 300 may include about 11520 fibers that have about 215×10⁻⁶ minner diameters (ID).

Although bioreactor housing 304 is depicted as cylindrical in shape, itcould have a variety of shapes, such as a rectangular cube. Bioreactorhousing 304 can be made of any type of biocompatible polymeric material,including a substantially transparent material that permits an observerto see one or more of the plurality of hollow fibers 316, as well asfluid residing within the bioreactor housing 304. Various otherbioreactor housings may differ in shape and size.

Referring now to FIG. 4, a portion of a CES 430 is shown in perspectiveview, and includes a back portion 434 of body 408 of the CES 430. Forclarity, the front portion the body 408 is not shown; however, the frontportion is attached to the back portion 434, such as by hinges 438,thereby allowing the front portion to comprise a door or hatch that canbe opened to access the bioreactor 300 of the CES 430. Attached to thebioreactor 300 may be a spool 416 for tubing and a sampling port 420.The environment in the vicinity of the bioreactor 300 is temperaturecontrolled to provide appropriate conditions for cell growth.

Referring now to FIG. 5, a flow chart 500 is shown that depicts oneembodiment of a cell expansion process associated with using a CES,including the steps associated with loading and distributing cells in abioreactor (e.g., bioreactor 300), as further described herein. Althoughfeatures of a CES (e.g., CES 430) are described as performing some ofthe steps of flow chart 500, the present invention is not limitedthereto. Indeed, other CES's with different features, not describedherein or described above (e.g., CES's 10, 800, or 900), may be utilizedin some embodiments. Accordingly, reference to features of CES 430 suchas bioreactor 300 are provided for illustrative purposes only, and theflow chart 500 is not limited to use with any specific CES.

Flow chart 500 starts at 502 and passes to 504 where a bioreactor 300and any associated tubing and related structures are connected to thebody 408 to provide an operable CES 430. Once connected to the body 408,the bioreactor 300 and its associated tubing and related structures areprimed at 508 using an appropriate priming fluid, such as saline. At512, cells are loaded and distributed in the bioreactor 300.

The loading and distributing of cells in embodiments involves a numberof substeps, for example, in some embodiments step 512 additionallyincludes optional steps of orienting the bioreactor 300 in a firstorientation at optional substep 516, and then loading and distributingthe cells in the bioreactor 300 at optional substep 520. At optionalsubstep 524, cells may be allowed to attach to the bioreactor.

Following loading and distributing cells in the bioreactor 300, thecells undergo expansion at 528. That is, the cells within the bioreactor300 are allowed to expand, i.e., grow and/or multiply. At 532, anassessment is made as to whether additional cells need to be added tothe bioreactor 300 and/or whether the bioreactor 300 needs to be rotatedto distribute cells within the bioreactor 300. If additional cells needto be loaded into the bioreactor 300 and/or if cells need to bedistributed in the bioreactor 300, then the flow chart 500 returns tostep 512. If cells do not need to be added and/or the bioreactor 300does not need to be rotated, then at 536 an assessment is made as towhether the cell expansion process 528 is complete. As used herein, thecell expansion process is determined to be complete if a sufficientnumber of cells and/or change in cell characteristics have beenachieved. If the cell expansion process 528 is complete, the cells areharvested at 540. If cell expansion process 528 is not complete, thenthe cell expansion process at 528 is allowed to continue. Flow chart 500ends at 544.

Additional detail is now provided regarding processes that may be usedto load, distribute and expand cells in a bioreactor and CES's, e.g.,steps 512 and 528 (FIG. 5), in some embodiments. FIGS. 6 and 7illustrate flow charts of some processes that may be used to load,distribute, attach and expand cells. These processes may be performed aspart of a process of flow chart 500, e.g., sub-steps of steps describedabove, e.g., steps 512 and 528. In other embodiments, the processesdescribed by flow chart 600 and 700 may be performed without regard tothe steps described in flow chart 500. Additionally, the steps in flowcharts 600 and 700 may be described below as being performed by, or withrespect to, a CES or portions thereof (e.g., CES's 10, 800, 900),including components (e.g., motors used as rocking components 402 and404), a bioreactor (e.g., bioreactors 24, 300, 400, 801, or 908); orportions of a bioreactor. This description is not intended to limit flowcharts 600 and 700, which in embodiments may have their steps performedby, or with respect to, other systems, devices, components, or features.

Flow chart 600 starts at 604, and passes to step 608 where fluid thatincludes cells may be circulated through a bioreactor such as bioreactor300 (see FIGS. 3 and 8-12). In embodiments, step 608 may involveactivating one or more pumps to circulate fluid through the bioreactor300. For example, an IC circulation pump (e.g., 812 or 911) may beactivated to circulate fluid through the IC side of bioreactor 300 at afirst circulation flow rate. In at least one embodiment, fluid carryingthe cells may pass through hollow fibers of the bioreactor 300 from theIC side to the EC side. In other embodiments, cells may be loaded intothe EC side of the bioreactor 300 and have the fluid carrying the cellspass from the EC side to the IC side. In these embodiments, an ECcirculation pump (e.g., 828 or 974) may be activated to circulate fluidthrough the EC side of bioreactor 300 at a first circulation flow rate.

Step 608 may in some embodiments involve also rotating the bioreactor300 in a particular sequence to facilitate distribution of the cellsthrough the bioreactor 300 and circulation paths of the CES to which thebioreactor 300 may be fluidly associated. Examples of embodiments forrotating bioreactor 300 in a particular sequence to facilitatedistribution of the cells during circulation or loading is described inU.S. patent application Ser. No. 12/968,483, filed on Dec. 15, 2010,entitled “METHOD OF LOADING AND DISTRIBUTING CELLS IN A BIOREACTOR OF ACELL EXPANSION SYSTEM,” which is hereby incorporated by reference in itsentirety as if set forth herein in full. In other embodiments, thecirculating step 608 may involve rotating the bioreactor 300 for someperiods of time, but maintaining the bioreactor 300 stationary for otherperiods of time.

After step 608, the fluid circulation rate is reduced at step 612. Thecirculation rate may be reduced to about zero (0) ml/min, or in otherembodiments may be reduced to a rate that is above zero (0) ml/min butstill allows cells to settle and attach to the bioreactor 300, e.g., aninside surface of hollow fibers 316 of bioreactor 300. In embodiments,step 612 may involve stopping or turning off one or more pumps used instep 608 to circulate the fluid.

Flow passes from step 612 to optional step 616, which may be performedto orient a bioreactor, e.g. bioreactor 300 to an initial orientation.In embodiments, a bioreactor may already be oriented in an initialorientation, which would make step 616 unnecessary. When performed, step616 may be performed by one or more motors in embodiments.

Referring now to FIGS. 8-12, a bioreactor 300 is shown in FIG. 8positioned in an initial orientation. As part of optional step 616,bioreactor 300 may be oriented with its longitudinal axis LA-LA in astarting orientation, such as, for example, a first horizontalorientation as shown in FIG. 8.

Flow passes from 616, to step 620 where the bioreactor is maintained ata first orientation to allow cells to settle and in some embodimentsattach to a first portion of bioreactor 300. Step 620 is performed for afirst predetermined period of time.

Referring now to FIGS. 13A-13C, these figures illustrate a cross-sectionof a hollow fiber 1300 (taken perpendicular to a central axis of thehollow fiber 1300 and a central axis of bioreactor 300) that may be oneof the hollow fibers 316 of bioreactor 300. These figures illustrate thepossible locations of cells within the hollow fibers 316 during somestep of flow chart 600. As illustrated in FIG. 13A, before thecirculation rate is reduced at step 612, cells within individual hollowfiber 1300 may be distributed, in embodiments evenly, throughout thevolume of hollow fiber 1300. When the circulation rate is reduced, thecells may begin to be influenced by gravity 1304 and begin to settle.

In embodiments, with the bioreactor 300 in the first horizontalorientation (FIG. 8), the cells within bioreactor 300 are allowed tosettle onto a first portion of the bioreactor. As illustrated in FIG.13B, the first portion of bioreactor 300 may include at least a portion1308 of hollow fiber 1300. In embodiments, the cells will be allowed tosettle for a first predetermined period of time (step 620 in flow chart600) that may be selected to not only allow the cells to settle, butalso to attach to portion 1308 of the hollow fiber 1300.

In some embodiments, the first predetermined period of time may be longenough in duration merely to allow the cells to settle and attach toportion 1308. In these embodiments, the cells may only need to travelthe distance of the inner diameter of hollow fiber 1308. For example, inembodiments where the hollow fiber has an inner diameter of betweenabout 150 microns and about 300 microns, the first predetermined periodof time may be less than about 20 minutes, less than about 15 minutes,or even less than about 10 minutes. In other embodiments, the firstpredetermined period of time may be greater than about 1 minute, greaterthan about 2 minutes, greater than about 3 minutes, or even greater thanabout 4 minutes. In one embodiment, the first period of time may bebetween about 3 minutes and about 8 minutes, such as about 5 minutes.

In other embodiments, the first predetermined period of time may be longenough in duration to not only allow cells to settle and attach to ahollow fiber, it may be long enough in duration to allow attached cellsto grow. In these embodiments, the cells may grow laterally since eitherlateral direction may provide the least resistance. In other words,because the cells on portion 1308 would be growing against the force ofgravity 1304 if they grew upward on the fiber wall, it is believe thatin embodiments, they may grow laterally, at least initially. In theseembodiments, when the cells are allowed to grow after attachment, thefirst predetermined period of time may be greater than about 5 hours,greater than about 10 hours, greater than about 15 hours, greater thanabout 20 hours, or even greater than about 24 hours. In otherembodiments, the first predetermined period of time may be less thanabout 60 hours, less than about 55 hours, less than about 50 hours, oreven less than about 45 hours. In one embodiment, the predeterminedperiod of time may be between about 10 hours and about 48 hours.

Referring back to FIG. 6, in some embodiments, after step 620, flowpasses to step 640, where the bioreactor 300 is rotated to a secondhorizontal orientation that is about 180 degrees from the firsthorizontal orientation. As shown in FIGS. 8-10, the bioreactor may berotated by first being rotated from its first horizontal orientation(FIG. 8) to a first vertical orientation, which is about 90 degrees fromthe first horizontal orientation, e.g. axis LA LA in a verticalorientation (FIG. 9). Bioreactor 300 may then be rotated another 90degrees (FIG. 10) to complete the rotation to the second horizontalorientation.

In embodiments, after rotation to the second horizontal orientation,flow 600 may pass to step 644, where the cell expansion is thenperformed with the bioreactor 300 in the second horizontal orientation.FIG. 13C illustrates that in the second horizontal orientation, thecells attached to hollow fiber 1300 are now positioned on a top insideportion of the hollow fiber 1300. Step 644 may involve a number ofsubsteps, such as circulating fluid into the bioreactor to feed andprovide nutrients to the cells attached in the bioreactor. As can beappreciated, step 644 may also involve providing oxygen to the cells sothat they may multiply. Several other parameters in the bioreactor maybe controlled in order to optimize the expansion, i.e. growth of thecells. In some embodiments, step 644 may include circulating fluid tofeed the cells for about 24 hours, about 36 hours, about 48 hours, about60 hours, or even about 72 hours. In some embodiments, the feeding ofthe cells as part of step 644 may be performed for less than about 120hours, less than about 108 hours, less than about 96 hours, less thanabout 84 hours, or even less than about 72 hours. Flow 600 may then endat 648.

Without being bound by theory, it is believed that in embodiments, thecell expansion is improved if the cells are grown as illustrated in FIG.13C under the influence of gravity. The cells may in embodiments growdownward in the hollow fiber 1300, toward portions of the hollow fiberthat do not have cells. It is believed that the cells may grow towardportions of the fiber that provide the least resistance, such asportions below the top portion 1308, see FIG. 13C. In embodiments,growing under the influence of gravity improves cell yield and reducescell doubling time, as compared to conventional processes.

In other embodiments, flow 600 may include additional steps. Forexample, in some embodiments, after step 620, flow 600 may pass to step624 where bioreactor 628 may be rotated to a vertical orientation. Forexample, bioreactor 300 may be rotated to a first vertical orientationas shown in FIG. 9. After step 624, flow may pass to step 628, where thebioreactor may be maintained in the first vertical orientation for asecond predetermined period of time.

Referring now to FIGS. 13D and 13E, these figures illustrate across-section of a hollow fiber 1300 (taken parallel to a central axisof the hollow fiber 1300 and a central axis of bioreactor 300) that maybe one of the hollow fibers 316 of bioreactor 300. FIGS. 13D and 13Eillustrate hollow fiber 1300 after step 620, where cells have settledand attached to a portion of the fiber 1300. As shown in FIG. 13D, whenbioreactor 300 is rotated to the first vertical orientation, a first end1312 of hollow fiber 1300 is positioned above a second end 1316.

As noted above, without being bound by theory, it is believed that thecells that are attached to fiber 1300 will be influenced by gravity 1304and begin to grow, i.e., expand, longitudinally toward end 1316.Therefore, in embodiments, step 628 (maintain first verticalorientation) is performed for a second predetermined period of time thatmay be long enough in duration to allow the cells to growlongitudinally. The second predetermined period of time may be in someembodiments, greater than about 5 hours, greater than about 10 hours,greater than about 15 hours, greater than about 20 hours, or evengreater than about 24 hours. In other embodiments, the secondpredetermined period of time may be less than about 60 hours, less thanabout 55 hours, less than about 50 hours, or even less than about 45hours. In one embodiment, the predetermined period of time may bebetween about 10 hours and about 48 hours.

After step 628, flow may pass to step 632, where the bioreactor may berotated to a second vertical orientation. One example of bioreactor 300in a second vertical orientation is shown in FIG. 12. After step 624,flow may pass to step 636, where the bioreactor may be maintained in thesecond vertical orientation for a third predetermined period of time.

Referring to FIG. 13E, this figure illustrates hollow fiber 1300 afterstep 632, where cells have settled and attached to a portion of thefiber 1300 and the bioreactor 300 has been rotated from a first verticalorientation to a second vertical orientation and is being maintained inthe second vertical orientation. As shown in FIG. 13E, when bioreactor300 is rotated to the second vertical orientation, the first end 1312 ofhollow fiber 1300 is positioned below the second end 1316.

Similar to step 628 (maintain first vertical orientation), step 636(maintain second vertical orientation) is performed because it isbelieved that in embodiments, the cells that are attached to fiber 1300will be influenced by gravity 1304 and begin to grow, i.e., expand,longitudinally toward end 1312. Step 636 may be performed in embodimentsfor a third predetermined of period of time that may be long enough induration to allow the cells to grow longitudinally toward end 1312 asshown in FIG. 13E. The third predetermined period of time may be in someembodiments, greater than about 5 hours, greater than about 10 hours,greater than about 15 hours, greater than about 20 hours, or evengreater than about 24 hours. In other embodiments, the secondpredetermined period of time may be less than about 60 hours, less thanabout 55 hours, less than about 50 hours, or even less than about 45hours. In one embodiment, the predetermined period of time may bebetween about 10 hours and about 48 hours.

Referring back to flow chart 600, after step 636, flow may pass to step640 where as described above, the bioreactor may be rotated to a secondhorizontal position as shown in FIG. 11. As described above, from step640, flow 600 passes to 644 where the cells are expanded, i.e.multiplied. Flow then ends at 648.

Turning now to FIG. 7, flow 700 begins at 704 and passes to step 708where fluid that includes cells may be circulated through a bioreactorsuch as bioreactor 300 (see FIGS. 3 and 8-12). In embodiments, step 708may involve activating one or more pumps to circulate fluid through thebioreactor 300. For example, an IC circulation pump (e.g., 812 or 911)may be activated to circulate fluid through the IC side of bioreactor300 at a first circulation flow rate. In at least one embodiment, fluidcarrying the cells may pass through hollow fibers of the bioreactor 300from the IC side to the EC side. In other embodiments, cells may beloaded into the EC side of the bioreactor 300 and have the fluidcarrying the cells pass from the EC side to the IC side. In theseembodiments, an EC circulation pump (e.g., 828 or 974) may be activatedto circulate fluid through the EC side of bioreactor 300 at a firstcirculation flow rate.

In embodiments, the first circulation flow rate may be a relatively highflow rate. In embodiments, the first circulation flow rate may be lessthan about 500 ml/min, less than about 400 ml/min, or even less thanabout 300 ml/min. In other embodiments, the first circulation rate maybe greater than about 50 ml/min, greater than about 100 ml/min, or evengreater than about 150 ml/min. In one embodiment, the first circulationflow rate is between about 100 ml/min and about 300 ml/min, such asabout 200 ml/min.

Step 708 may in some embodiments involve also rotating the bioreactor300 in a particular sequence to facilitate distribution of the cellsthrough the bioreactor 300 and circulation paths of the CES to which thebioreactor 300 may be fluidly associated. In other embodiments, thecirculating step 708 may involve rotating the bioreactor 300 for someperiods of time, but maintaining the bioreactor 300 stationary for otherperiods of time.

After step 708, the fluid circulation rate is reduced at step 712. Thecirculation rate may be reduced to about zero (0) ml/min, or in otherembodiments may be reduced to a rate that is above zero (0) ml/min butstill allows cells to settle and attach to the bioreactor 300, e.g., aninside surface of hollow fibers 316 of bioreactor 300. In embodiments,step 712 may involve stopping or turning off one or more pumps used instep 708 to circulate the fluid.

Flow passes from step 712 to optional step 716, which may be performedto orient a bioreactor, e.g. bioreactor 300 to an initial orientation.In embodiments, a bioreactor may already be oriented in an initialorientation, which would make step 716 unnecessary. When performed, step716 may in some embodiments be performed by one or more motors.

Referring now to FIGS. 8-12, a bioreactor 300 is shown in FIG. 8positioned in an initial orientation. As part of optional step 716,bioreactor 300 may be oriented with its longitudinal axis LA-LA in astarting orientation, such as, for example, a first horizontalorientation as shown in FIG. 8.

Flow passes from 716, to step 720 where the bioreactor is maintained ata first orientation to allow cells to settle and in some embodimentsattach to a first portion of bioreactor 300. Step 820 is performed for afirst predetermined period of time.

Referring now to FIGS. 14A-14D and FIGS. 15A-15F these figuresillustrate a cross-section of a hollow fiber 1400 (taken perpendicularto a central axis of the hollow fiber 1400 and a central axis ofbioreactor 300) that may be one of the hollow fibers 316 of bioreactor300. These figures illustrate the possible locations of cells within thehollow fibers 316 during some steps of flow chart 700. As illustrated inFIG. 14A, before the circulation rate is reduced at step 712, cellswithin individual hollow fiber 1400 may be distributed, in embodimentsevenly, throughout the volume of hollow fiber 1400. When the circulationrate is reduced, the cells may begin to be influenced by gravity 1404and begin to settle. FIG. 15A also illustrates a similar situation withrespect to a hollow fiber 1500 and gravity 1504.

In embodiments, with the bioreactor 300 in the first horizontalorientation (FIG. 8), the cells within bioreactor 300 are allowed tosettle onto a first portion of the bioreactor. As illustrated in FIGS.14B and 15B, the first portion of bioreactor 300 may include at least aportion 1408 of hollow fiber 1400 and/or portion 1508 in hollow fiber1500. In embodiments, the cells will be allowed to settle for a firstpredetermined period of time that may be selected to not only allow thecells to settle, but also to attach to portion 1408 of the hollow fiber1400 (and 1508 of hollow fiber 1500).

In some embodiments, the first predetermined period of time may be longenough in duration to allow the cells to settle and attach to portion1408 and 1508. In these embodiments, the cells may only need to travelthe distance of the inner diameter of hollow fiber 1400 or 1500. Forexample, in embodiments where the hollow fiber has an inner diameter ofbetween about 150 microns and about 300 microns, the first predeterminedperiod of time may be less than about 20 minutes, less than about 15minutes, or even less than about 10 minutes. In other embodiments, thefirst predetermined period of time may be greater than about 1 minute,greater than about 2 minutes, greater than about 3 minutes, or evengreater than about 4 minutes. In one embodiment, the first period oftime may be between about 3 minutes and about 8 minutes, such as about 5minutes.

After step 720, flow passes to step 724, where the bioreactor 300 isrotated to a second horizontal orientation that is about 180 degreesfrom the first horizontal orientation. As shown in FIGS. 8-10, thebioreactor may be rotated by first being rotated from its firsthorizontal orientation (FIG. 8) to a first vertical orientation, whichis about 90 degrees from the first horizontal orientation, e.g. axis LALA in a vertical orientation (FIG. 9). Bioreactor 300 may then berotated another 90 degrees (FIG. 10) to complete the rotation to thesecond horizontal orientation. Step 724 may in some embodiments beperformed by one or more motors connected to bioreactor 300. Thesemotors may be part of a rocking device.

In some embodiments, flow 700 will pass from step 724 to step 736 wherethe bioreactor 300 is maintained in the second horizontal orientation(FIG. 10) for a second predetermined period of time so that the cellsare allowed to settle to a second portion of the bioreactor, such asportion 1412 of hollow fiber 1400 (FIG. 14C) or portion 1512 of hollowfiber 1500 (FIG. 15C).

In some embodiments, flow 700 may include optional steps 728 and 732prior to proceeding to step 736. Similar to step 708, step 728 providesfor circulating fluid through the bioreactor 300. In embodiments, step728 may involve activating one or more pumps to circulate fluid throughthe bioreactor 300. As noted above, an IC circulation pump (e.g., 812 or911) may be activated to circulate fluid through the IC side ofbioreactor 300 at a second circulation flow rate. In at least oneembodiment, fluid carrying the cells may pass through hollow fibers ofthe bioreactor 300 from the IC side to the EC side. In otherembodiments, cells may be loaded into the EC side of the bioreactor 300and have the fluid carrying the cells pass from the EC side to the ICside. In these embodiments, an EC circulation pump (e.g., 828 or 974)may be activated to circulate fluid through the EC side of bioreactor300 at a second circulation flow rate.

In embodiments, the second circulation flow rate may be less than thefirst circulation rate. In embodiments, the second circulation flow ratemay be less than about 400 ml/min, less than about 300 ml/min, or evenless than about 200 ml/min. In other embodiments, the second circulationrate may be greater than about 25 ml/min, greater than about 500 ml/min,or even greater than about 75 ml/min. In one embodiment, the secondcirculation flow rate is between about 50 ml/min and about 150 ml/min,such as about 100 ml/min.

In some embodiments, step 728 may also involve circulation in adifferent direction than the circulation performed in step 708. In otherwords, in some embodiments, step 708 may involve circulating fluid in acounter clockwise direction (see IC loop in FIGS. 8 and 9). In someembodiments, the circulation at step 728 may be clockwise. In otherwords, the circulation may flow opposite to the circulation at step 708.In other embodiments, the circulation in step 708 may flow in the samedirection as step 708, clockwise or counter clockwise.

Optional step 728 may in some embodiments involve also rotating thebioreactor 300 in a particular sequence to facilitate distribution ofthe cells through the bioreactor 300 and circulation paths of the CES towhich the bioreactor 300 may be fluidly associated. In otherembodiments, the circulating step 728 may involve rotating thebioreactor 300 for some periods of time, but maintaining the bioreactor300 stationary for other periods of time.

After optional step 728, the fluid circulation rate is once againreduced at step 732. The circulation rate may be reduced to about zero(0) ml/min, or in other embodiments may be reduced to a rate that isabove zero (0) ml/min but still allows cells to settle and attach to thebioreactor 300, e.g., an inside surface of hollow fibers 316 ofbioreactor 300. In embodiments, step 732 may involve stopping or turningoff one or more pumps used in step 728 to circulate the fluid.

Referring once again to step 736, maintaining the bioreactor in thesecond horizontal orientation allows cells to settle on portion 1412 (or1512 in FIG. 15C), which may be opposite portion 1408, e.g., portion1408 (or 1508) may be referred to as a “bottom portion” and portion 1412(or 1512 in FIG. 15C) may be referred to as a “top portion.” FIGS. 14Cand 15C illustrate cells settling onto portions 1412 and 1512, or insome embodiments vice versa. In embodiments, the cells will be allowedto settle for a second predetermined period of time that may be selectedto not only allow the cells to settle, but also to attach to portion1412 of the hollow fiber 1400 (or 1512 of fiber 1500).

In some embodiments, the second predetermined period of time may be longenough in duration allow the cells to settle and attach to portion 1412(or 1512 in FIG. 15C). In these embodiments, the cells may only need totravel the distance of the inner diameter of hollow fiber 1400 or 1500.For example, in embodiments where the hollow fiber has an inner diameterof between about 150 microns and about 300 microns, the secondpredetermined period of time may be less than about 20 minutes, lessthan about 15 minutes, or even less than about 10 minutes. In otherembodiments, the second predetermined period of time may be greater thanabout 1 minute, greater than about 2 minutes, greater than about 3minutes, or even greater than about 4 minutes. In one embodiment, thesecond period of time may be between about 3 minutes and about 8minutes, such as about 5 minutes.

In some embodiments, after step 736, flow 700 may pass to step 772 wherecells are expanded. Step 772 may involve a number of substeps, such ascirculating fluid into the bioreactor to feed and provide nutrients tothe cells attached in the bioreactor. As can be appreciated, step 772may also involve providing oxygen to the cells so that they maymultiply. Several other parameters in the bioreactor may be controlledin order to optimize the expansion, i.e. growth of the cells. In someembodiments, step 772 may include circulating fluid to feed the cellsfor about 24 hours, about 36 hours, about 48 hours, about 60 hours, oreven about 72 hours. In some embodiments, the feeding of the cells aspart of step 772 may be performed for less than about 120 hours, lessthan about 108 hours, less than about 96 hours, less than about 84hours, or even less than about 72 hours. FIG. 14D illustrates hollowfiber 1400 for this embodiment. Flow then ends at 776.

In other embodiments, flow 700 may pass to step 740, where thebioreactor 300 is rotated back to its original first horizontalorientation. FIG. 11 illustrates bioreactor 300 once it has been rotatedback to its first horizontal orientation. Step 740 may be performed byone or more motors connected to bioreactor 300. These motors may be partof a rocking device. In embodiments, flow may pass from step 740 to step772 where the cells are expanded. Flow then ends at 776.

In other embodiments, flow 700 passes from step 740 to step 744, or inother embodiments, flow may pass directly from step 736, to step 744(when no additional rotation is performed), where fluid is againcirculated but at a third circulation flow rate. Similar to steps 708and 728, fluid is circulated through the bioreactor 300. In embodiments,step 744 may involve activating one or more pumps to circulate fluidthrough the bioreactor 300. As noted above, an IC circulation pump(e.g., 812 or 911) may be activated to circulate fluid through the ICside of bioreactor 300 at a third circulation flow rate. In at least oneembodiment, fluid carrying the cells may pass through hollow fibers ofthe bioreactor 300 from the IC side to the EC side. In otherembodiments, cells may be loaded into the EC side of the bioreactor 300and have the fluid carrying the cells pass from the EC side to the ICside. In these embodiments, an EC circulation pump (e.g., 828 or 974)may be activated to circulate fluid through the EC side of bioreactor300 at the third circulation flow rate.

In embodiments, the third circulation flow rate may be less than thesecond circulation rate. In embodiments, the third circulation flow ratemay be less than about 200 ml/min, less than about 150 ml/min, or evenless than about 100 ml/min. In other embodiments, the third circulationrate may be greater than about 10 ml/min, greater than about 20 ml/min,or even greater than about 30 ml/min. In one embodiment, the thirdcirculation flow rate is between about 20 ml/min and about 100 ml/min,such as about 50 ml/min.

In some embodiments, step 744 may also involve circulation in adifferent direction than the circulation performed in step 728. In otherwords, in some embodiments, step 728 may involve circulating fluid in aclockwise direction. In some embodiments, the circulation at step 744may be similar to step 708 and be in a counter clockwise direction (seeIC loop in FIGS. 8 and 9). In other words, the circulation at step 744may flow opposite to the circulation at step 728, and the same as thedirection of circulation of step 708. In other embodiments, thecirculation in steps 708, 728, 744 may flow in the same direction,clockwise or counter clockwise.

Optional step 744 may in some embodiments involve also rotating thebioreactor 300 in a particular sequence to facilitate distribution ofthe cells through the bioreactor 300 and circulation paths of the CES towhich the bioreactor 300 may be fluidly associated. In otherembodiments, the circulating step 744 may involve rotating thebioreactor 300 for some periods of time, but maintaining the bioreactor300 stationary for other periods of time.

Flow passes from 744 to step 748, where, the fluid circulation rate isonce again reduced. The circulation rate may be reduced to about zero(0) ml/min, or in other embodiments may be reduced to a rate that isabove zero (0) ml/min but still allows cells to settle and attach to thebioreactor 300, e.g., an inside surface of hollow fibers 316 ofbioreactor 300. In embodiments, step 748 may involve stopping or turningoff one or more pumps used in step 744 to circulate the fluid.

From step 748, flow passes to step 752 where the bioreactor ismaintained in a horizontal orientation. In those embodiments thatinclude step 744 (rotate to first orientation), step 752 will involvemaintaining the first horizontal orientation. In those embodiments thatdo not include the rotation of step 740, step 752 will involvemaintaining the second horizontal orientation. In any case, step 752 isperformed to allow cells to settle again, such as on portion 1508 (SeeFIGS. 15D and 15E; if the rotation step 740 is performed). Inembodiments, the cells will be allowed to settle for a thirdpredetermined period of time that may be selected to not only allow thecells to settle, but also to attach.

In some embodiments, the third predetermined period of time may be longenough in duration to allow the cells to settle and attach to portion1508. In these embodiments, the cells may only need to travel thedistance of the inner diameter of hollow fiber 1500. For example, inembodiments where the hollow fiber 1500 has an inner diameter of betweenabout 150 microns and about 300 microns, the third predetermined periodof time may be less than about 20 minutes, less than about 15 minutes,or even less than about 10 minutes. In other embodiments, the thirdpredetermined period of time may be greater than about 1 minute, greaterthan about 2 minutes, greater than about 3 minutes, or even greater thanabout 4 minutes. In one embodiment, the third period of time may bebetween about 3 minutes and about 8 minutes, such as about 5 minutes.

In some embodiments, flow 700 may pass from step 752 to step 772 wherethe cells are expanded. FIG. 15F illustrates fiber 1500 in theseembodiments. Flow would then end at 776.

In other embodiments, as described below, flow 700 may includeadditional rotation (756), circulation (760), reduce circulation (764),and maintain orientation (768) steps before moving to step 772 wherecells are expanded. In these embodiments, flow 700 may pass from step752 to step 756, where the bioreactor 300 is rotated back to the secondhorizontal orientation, if it was rotated at step 740 to the firsthorizontal orientation. FIG. 10 illustrates bioreactor 300 in the secondhorizontal orientation. Step 756 may be performed by one or more motorsconnected to bioreactor 300. These motors may be part of a rockingdevice. In some embodiments, this step may be unnecessary, if step 740was not performed to rotate the bioreactor to the first horizontalorientation.

Flow 700 passes to step 760 where fluid is again circulated but at afourth circulation flow rate. Similar to steps 708, 728, and 744, fluidis circulated through the bioreactor 300. In embodiments, step 744 mayinvolve activating one or more pumps to circulate fluid through thebioreactor 300, as noted above, an IC circulation pump (e.g., 812 or911) may be activated to circulate fluid through the IC side ofbioreactor 300 at a fourth circulation flow rate. In at least oneembodiment, fluid carrying the cells may pass through hollow fibers ofthe bioreactor 300 from the IC side to the EC side. In otherembodiments, cells may be loaded into the EC side of the bioreactor 300and have the fluid carrying the cells pass from the EC side to the ICside. In these embodiments, an EC circulation pump (e.g., 828 or 974)may be activated to circulate fluid through the EC side of bioreactor300 at the fourth circulation flow rate.

In embodiments, the fourth circulation flow rate may be less than thethird circulation rate. In embodiments, the fourth circulation flow ratemay be less than about 100 ml/min, less than about 75 ml/min, or evenless than about 50 ml/min. In other embodiments, the fourth circulationrate may be greater than about 5 ml/min, greater than about 10 ml/min,or even greater than about 15 ml/min. In one embodiment, the fourthcirculation flow rate is between about 15 ml/min and about 35 ml/min,such as about 25 ml/min.

In some embodiments, step 760 may also involve circulation in adifferent direction than the circulation performed in step 744. In otherwords, in some embodiments, step 744 may involve circulating fluid in acounter clockwise direction. In some embodiments, the circulation atstep 760 may be similar to step 728 and be in a clockwise direction. Inother words, the circulation at step 760 may flow opposite to thecirculation at step 744, and the same as the direction of circulation ofstep 728. In other embodiments, the circulation in steps 708, 728, 744and 760 may flow in the same direction, clockwise or counter clockwise.

Step 760 may in some embodiments involve also rotating the bioreactor300 in a particular sequence to facilitate distribution of the cellsthrough the bioreactor 300 and circulation paths of the CES to which thebioreactor 300 may be fluidly associated. In other embodiments, thecirculating step 760 may involve rotating the bioreactor 300 for someperiods of time, but maintaining the bioreactor 300 stationary for otherperiods of time.

Flow passes from 760 to step 764, where, the fluid circulation rate isonce again reduced. The circulation rate may be reduced to about zero(0) ml/min, or in other embodiments may be reduced to a rate that isabove zero (0) ml/min but still allows cells to settle and attach to thebioreactor 300, e.g., an inside surface of hollow fibers 316 ofbioreactor 300. In embodiments, step 764 may involve stopping or turningoff one or more pumps used in step 760 to circulate the fluid.

From step 764, flow passes to step 768 where the bioreactor ismaintained in the second horizontal orientation to allow cells to settleon for example portion 1512 again (see FIG. 15F). In embodiments, thecells will be allowed to settle for a fourth predetermined period oftime that may be selected to not only allow the cells to settle, butalso to attach once again.

In some embodiments, the fourth predetermined period of time may be longenough in duration allow the cells to settle and attach. In theseembodiments, the cells may only need to travel the distance of the innerdiameter of the hollow fiber, e.g., fiber 1500. For example, inembodiments where the hollow fiber 1500 has an inner diameter of betweenabout 150 microns and about 300 microns, the fourth predetermined periodof time may be less than about 20 minutes, less than about 15 minutes,or even less than about 10 minutes. In other embodiments, the fourthpredetermined period of time may be greater than about 1 minute, greaterthan about 2 minutes, greater than about 3 minutes, or even greater thanabout 4 minutes. In one embodiment, the fourth period of time may bebetween about 3 minutes and about 8 minutes, such as about 5 minutes.

After step 768, flow 700 passes to step 772 where the cells settled andattached to the bioreactor 300, e.g., to hollow fibers of thebioreactor, are expanded, i.e., multiplied. Flow 700 then ends at 776.

Without being bound by theory, it is believe that in embodiments, thecell expansion is improved if the steps of flow 700 are performed. It isbelieved that these embodiments help to ensure that more portions of thebioreactor, e.g., surface of hollow fibers in the bioreactor, are seededwith cells prior to cell expansion. This may provide for more cells toinitially be seeded, and ultimately may improve cell yield and reducecell doubling time, as compared to conventional processes.

Although flow 700 includes specific number of steps that provide forrotating, circulating, reducing circulation, and maintaining theorientation of the bioreactor, other embodiments are not limited tothese specific number of steps. In other embodiments, even after step768, the bioreactor may be rotated again, circulation can be restartedagain, followed by another period of reducing circulation to allow cellsto settle and maintain the orientation for a period of time to allowcells to attach to portion of a bioreactor. These steps may be performedany number of times. In embodiments, each time the circulation isrestarted, it is at a lower rate than the previous circulation. In otherembodiments, the circulation rates may be the same each time circulationis started. In yet other embodiments, the direction of circulation maybe changed, with circulation in a first direction, followed by stoppingthe circulation to allow the cells to settle and attach, circulation ina direction opposite the first direction (clockwise vs. counterclockwise) and again stopping the circulation to allow the cells tosettle.

Referring now to FIG. 16, a cross section 1600 (perpendicular to acentral axis) of a bioreactor (e.g., bioreactor 300) is shown. The crosssection 1600 illustrates a plurality of hollow fibers 1608 which may bewithin a housing 1604. The cross section 1600 is taken from one end of abioreactor and illustrates, in addition to the hollow fibers 1608 amatrix material 1628 (which may be referred to above as pottingmaterial) that holds the hollow fibers 1608 together.

Also shown in FIG. 16 are zones 1612, 1616, 1620 and 1624. These zonesrepresent fibers that may have fluid circulating through them atdifferent flow rates. In other words, without being bound by theory, itis believed that circulation at relatively high flow rates, such asrates that may be used in circulation steps 708 or 728 (FIG. 7) mayprimarily flow through fibers in zone 1612. Without being bound bytheory, it is believed that the higher flow rates do not allow fluid todisperse enough to flow evenly into the hollow fibers in the outerzones. As the flow rate is reduced, such as in steps 744 and 760, it isbelieved that the fluid may disperse into hollow fibers in outer zones,such as 1616, 1620 and 1624.

Accordingly, without being bound by theory, it is believed that havingsteps 708, 728, 744 and 752 circulate at different flow rates, allowsthe fluid to flow through more of the hollow fibers 1608 than if just asingle flow rate would be used. In one embodiment of a process thatfollows flow chart 700, at step 708 (at the flow rates described above),fluid may flow through the hollow fibers in zone 1612. At step 728 (atthe flow rates described above), fluid may flow through the hollowfibers in both zones 1612 and 1616 because the rate is slower and thefluid may disperse more. At step 744 (at the flow rates describedabove), fluid may flow through the hollow fibers in zones 1612, 1616,and 1620 because the flow rate is yet slower and fluid may disperse evenmore. At step 752 (at the flow rates described above), fluid may flowthrough the hollow fibers in all the zones 1612, 1616, 1620 and 1624because the flow rates are even slower and the fluid may dispersethrough all of the fibers in the various zones. Thus, it is believe thatfluid with the cells may flow into more of the hollow fibers using asequence of different flow rates, than if a single high flow ratecirculation is used.

Furthermore, it is also believed that the different flow rates may alsoaffect the longitudinal distribution of cells along the bioreactor,e.g., along a hollow fiber. That is, a higher flow rate may allow cellsto flow further along inside a hollow fiber. For example, at a higherflow rate, a cell being carried by fluid may reach beyond half thelength of the hollow fiber. At a lower flow rate, a cell being carriedby fluid may reach half the length of the hollow fiber. At even a lowerflow rate, a cell being carried by fluid may reach less than half thelength of the hollow fiber. Accordingly, in some embodiments, it isbelieved that the use of different flow rates may provide someimprovement in longitudinal distribution of cells along the length ofthe bioreactor, e.g., a hollow fiber.

It is noted that the embodiments described with respect to flow charts500, 600 and 700 may be used in the expansion of any type of cell somenon-limiting examples including, stem cells (mesenchymal, hematopoietic,etc.), fibroblasts, keratinocytes, progenitor cells, endothelial cells,other fully differentiated cells and combinations thereof. Differentcells may be expanded using processes that have different features, andcombinations of features, some of which may include steps describedabove with respect to flow charts 500, 600 and/or 700.

Although flow charts 500 (FIG. 5), 600 (FIG. 6) and 700 (FIG. 7) havebeen described with steps listed in a particular order, the presentinvention is not limited thereto. In other embodiments, steps may beperformed in different order, in parallel, or any different number oftimes, e.g., before and after another step. Also, as indicated above,flow charts 500, 600 and 700 may include some optional steps orsub-steps. However, those steps above that are not indicated as optionalshould not be considered as essential to the invention, but may beperformed in some embodiments of the present invention and not inothers.

Finally, FIG. 17 illustrates example components of a basic computersystem 1700 upon which embodiments of the present invention may beimplemented. Computer system 1700 may perform some steps in the methodsfor loading and distributing cells. System 1700 may be a controller forcontrolling features, e.g., flow control devices, pumps, valves,rotation of bioreactors, motors, etc., of CES systems 10, 430, 800, and900 shown above in which cells are loaded and distributed for expansion.

Computer system 1700 includes output device(s) 1704, and/or inputdevice(s) 1708. Output device(s) 1704 may include one or more displays,including CRT, LCD, and/or plasma displays. Output device(s) 1704 mayalso include a printer, speaker, etc. Input device(s) 1708 may include akeyboard, touch input devices, a mouse, voice input device, etc.

Basic computer system 1700 may also include a processing unit 1712and/or a memory 1716, according to embodiments of the present invention.The processing unit 1712 may be a general purpose processor operable toexecute instructions stored in memory 1716. Processing unit 1712 mayinclude a single processor or multiple processors, according toembodiments. Further, in embodiments, each processor may be a multi-coreprocessor having one or more cores to read and execute separateinstructions. The processors may include general purpose processors,application specific integrated circuits (ASICs), field programmablegate arrays (FPGAs), other integrated circuits.

The memory 1716 may include any tangible medium for short-term orlong-term storage for data and/or processor executable instructions,according to embodiments. The memory 1716 may include, for example,Random Access Memory (RAM), Read-Only Memory (ROM), or ElectricallyErasable Programmable Read-Only Memory (EEPROM). Other storage media mayinclude, for example, CD-ROM, tape, digital versatile disks (DVD) orother optical storage, tape, magnetic disk storage, magnetic tape, othermagnetic storage devices, etc. In embodiments, system 1700 may be usedto control the rotation of bioreactor 300 and/or various flow controldevices, pumps, valves, etc. of CES systems. Memory 1716 can storeprotocols 1720 and procedures 1724, such as protocols and procedures forloading and distributing cells in a bioreactor, which would controloperation of circulation pumps, valves, rotation of bioreactor(s), etc.

Storage 1728 may be any long-term data storage device or component.Storage 1220 may include one or more of the systems described inconjunction with memory 1716, according to embodiments. Storage 1728 maybe permanent or removable. In embodiments, system 1700 is part of a CESsystem and storage 1728 may store various procedures for utilizing a CESsystem to load, distribute, attach, expand, and harvest cells of varioustypes.

EXAMPLES

Below, some examples of specific embodiments of the present inventionare described. However, it is noted that although specific parameters,features, and/or values are described below, e.g., for programming a CES(namely a QUANTUM® cell expansion system), according to someembodiments, these are provided merely for illustrative purposes, andthe present invention is not limited to the specific details providedbelow.

Example 1

The objective of this study is to characterize the expansion of humanbone marrow derived mesenchymal stem cells (hMSCs) using two unique cellseeding methodologies in the QUANTUM® cell expansion system.

The current cell loading procedure used on the QUANTUM cell expansionsystem for pre-selected hMSCs distributes the cells in the bioreactorvia uniform cell suspension. The cells are loaded into the ICCirculation loop of the QUANTUM cell expansion system and thencirculated at relatively high flow rates (200 mL/min) for two minutes.This circulation method, coinciding with deliberate bioreactor motion,results in a uniform suspension of cells. Once the cells are uniformlysuspended, circulation and bioreactor motion stops and the cells settleonto the bioreactor surface.

One limitation of this cell loading procedure is that only the trough ofthe bioreactor fiber is seeded with cells. hMSCs are frequently seededat a specified cell density (e.g., 500 cells/cm²). In order to achieve aspecified seed density, only approximately 50% of the bioreactor surfacearea can be considered when determining the appropriate number of cellsto load. At 500 cells/cm², the QUANTUM cell expansion system bioreactorcan be seeded with 10.5E+06 cells (500 cells/cm²×21000 cm²). However,only 50% of the bioreactor surface area can be considered “seed able”due to the aforementioned mechanics of the current cell load protocol.In addition, expanding cells attempting to migrate to the “unseedable”surface of the bioreactor must overcome gravity in order to utilize thatsurface. It is theorized here that migrating cells may take the path ofleast resistance; resulting in rapid confluence within the cellpopulation compared to those expanded in its flask counter-part.

A total of seven sterilized Quantum CES Disposable sets with abioreactor may be fibronectin coated (5 mg) overnight. All Quantumsystems may be seeded with pre-cultured hMSCs. One Quantum cellexpansion system may use the current Load with Circulation Task andserve as the experiment control. Three Quantum cell expansion systemsmay use “Load with Circulation Task: Modification 1” (Modification 1)and three Quantum cell expansion systems may use “Load with CirculationTask: Modification 2” (Modification 2).

Disposable Sets: All bioreactors may be integrated into a QUANTUM cellexpansion system (CES) disposable set and sterilized with ethyleneoxide.

Cell Source and Density: The bioreactor that may be used may have a 2.1m² inner (IC) surface area. As a result, an adjustment to seedingdensities for control flasks may need to be made based on the bioreactorvolume fraction of the IC loop. All bioreactors may be uniformly loadedwith a maximum of 20E+06 pre-selected MSCs (existing passages 1-3) froma direct re-load of the same cell source. Cells from a single donor arepreferred. Seed three (3) T25 control flasks with hMSCs at the samedensity per cm² as the bioreactor for comparative purposes.

CES Media IC Input Q Management & Harvest: The media feed rate (IC InputQ) may be doubled when the glucose levels fall below 70 mg/dL; the ICInput Q may be doubled a second time in the course of one day if theglucose values continue to fall below 70 mg/dL. All disposable sets maybe harvested at the same time and no later than Day 8 to limit potentialaggregation. Cell harvest time may be determined as a result of themetabolic characteristics displayed by the cell cultures. The targetharvest time may be post-log phase growth of the cells.

Post-Harvest Evaluation: Evaluations may be performed on each of theharvest products. These evaluations may include cell count andviability.

Quantum CES Cell Load Modification 1

The current cell load procedure may be performed with the followingmodifications shown in bold. After allowing the cells to attach for 5minutes, all bioreactors may be rotated 180 degrees to allow unattachedcells to settle to the top of the hollow fiber membrane for anadditional 5 minutes. Then bioreactor may be rotated back to the homehorizontal position and proceed with the expansion protocol. Therationale for the modification is to distribute the cells over theentire surface area of the bioreactor hollow fiber.

Day: 0 Attach Cells with One (1) Rotation

Purpose: enables adherent cells to attach to the bioreactor membranewhile allowing flow on the EC circulation loop. The pump flow rate tothe IC loop may be set to zero.

Table 1 describes the bags of solution that may be attached to each linewhen performing Attach Cells. These solutions and corresponding volumesare based on the default settings for this task.

Table 1: Solutions for Attach Cells Modification 1

TABLE 1 Solutions for Attach Cells Table 1: Solutions for Attach CellsVolume (estimate based Bag Solution in Bag on factory default) CellInlet None N/A Reagent None N/A IC Media Media with Protein 6 mL/hourWash None N/A EC Media None N/A

Cells Pathway: Task>Load and Attach>Attach Cells

Enter the values for each setting for Attach Cells shown in ProtocolTable 2 a-c.

TABLE 2a Task > Load and Attach > Attach Cells, Step 1 Modification 1Table 2a: Task Settings for Attach Cells, Step 1 Laboratory SettingFactory Default Default Modifications IC Inlet None IC Inlet Rate 0 ICCirculation Rate 0 EC Inlet [EC Media] IC Media EC Inlet Rate 0 ECCirculation Rate 0 Outlet EC Waste Rocker Control [Stationary (0°)]Stationary 180° Stop Condition [Manual] Time: 5 minutes

TABLE 2b Task > Load and Attach > Attach Cells, Step 2 Modification 1Table 2b: Task Settings for Attach Cells, Step 2 Laboratory SettingFactory Default Default Modifications IC Inlet None IC Inlet Rate 0 ICCirculation Rate 0 EC Inlet [EC Media] IC Media EC Inlet Rate 0 ECCirculation Rate 0 Outlet EC Waste Rocker Control Stationary (0°) StopCondition [Manual] Time: 5 minutes

TABLE 2c Task > Load and Attach > Attach Cells, Step 3 Modification 1Table 2c: Task Settings for Attach Cells, Step 3 Laboratory SettingFactory Default Default Modifications IC Inlet None IC Inlet Rate 0 ICCirculation Rate 0 EC Inlet [EC Media] IC Media EC Inlet Rate   0.1 ECCirculation Rate 30  Outlet EC Waste Rocker Control [Stationary (0°)]Stationary 180° Stop Condition Manual

Quantum CES Cell Load Modification 2

The current cell load procedure, pre-selected MSC Expansion Protocol,may be performed with the following modifications shown in bold. Cellsmay be attached to the top of the hollow fiber by rotating thebioreactor to the 180 degree position during the cell attachment phase(18-24 hours). Then rotate the bioreactor back to the home position andproceed with the expansion protocol. The rationale for the modificationis to allow gravity to influence the direction of cell migration towardthe empty growth surface during cell expansion.

The force of gravity may be used to “influence” the cell migrationduring expansion. This may be accomplished by seeding the cells asdescribed in the current cell load procedure, then during expansion thebioreactor may be rotated 180°. In this configuration the unoccupiedgrowth surface of the bioreactor is below the seeded cells. The cellsmay then expand in the direction of least resistance (e.g., downward,aided by gravity).

Day: 0 Attach Cells with One (1) Rotation

Purpose: enables adherent cells to attach to the bioreactor membranewhile allowing flow on the EC circulation loop. The pump flow rate tothe IC loop may be set to zero.

Table 5 describes the bags of solution that may be attached to each linewhen performing Attach Cells. These solutions and corresponding volumesare based on the default settings for this task.

TABLE 5 Solutions for Attach Cells Modification 2 Table 5: Solutions forAttach Cells Volume (estimate based Bag Solution in Bag on factorydefault) Cell Inlet None N/A Reagent None N/A IC Media Media withProtein 6 mL/hour Wash None N/A EC Media None N/A

Cells Pathway: Task>Load and Attach>Attach Cells

TABLE 6 Task > Load and Attach > Attach Cells Modification 2 Table 6:Task Settings for Attach Cells, Step 1 Laboratory Setting FactoryDefault Default Modifications IC Inlet None IC Inlet Rate 0 ICCirculation Rate 0 EC Inlet [EC Media] IC Media EC Inlet Rate   0.1 ECCirculation Rate 30  Outlet EC Waste Rocker Control [Stationary (0°)]Stationary 180° Stop Condition Manual

The results may be as follows:

TABLE 7 Quantum hMSC hMSC Harvest Harvest Percent Run ModificationSeeding Seeding//cm² hMSC hMSC/cm² Increase Q621 Control 1.05E+07 5002.56E+08 12,194  0% Q622 Mod 1 1.05E+07 500 3.02E+08 14,376 18% Q623 Mod1 1.05E+07 500 3.70E+08 17,620 36% Q624 Mod 1 1.05E+07 500 3.49E+0816,596 51%

TABLE 8 Quantum hMSC hMSC Harvest Harvest Percent Run ModificationSeeding Seeding//cm² hMSC hMSC/cm² Increase Control 1.05E+07 5002.56E+08 12,194  0% Average Mod 1 1.05E+07 500 3.40E+08 16,197 35%

TABLE 9 # of Cells # Cells Doubling Load Condition Seeded Harvested Time(hrs) Control 10.5 × 10⁶ 256 × 10⁶ 34.9 Gravity Influenced Expansion10.5 × 10⁶ 345 × 10⁶ 30.9 (Modification 2) Gravity Influenced Expansion10.5 × 10⁶ 347 × 10⁶ 31.9 (Modification 2) Gravity Influenced Expansion10.5 × 10⁶ 388 × 10⁶ 31.9 (Modification 2)

Example 2

The Bull's Eye cell loading procedure is a series of steps designed toincrease cell yield by allowing for a more even distribution of cellswithin the bioreactor of the QUANTUM® cell expansion system and byreducing the number of cells lost during a seeding process.

The Bull's Eye cell loading technique for the QUANTUM cell expansionsystem provides a series of steps that include and add to the ‘LoadCells with Uniform Suspension’ protocol (Quantum Cell Expansion SystemOperator's Manual for Software Version 2.0) that is commonly used toseed the bioreactor. In Load Cells with Uniform Suspension (LCWUS),suspended cells have a single opportunity to enter and attach to theinternal surface of one fiber of the bioreactor after the cellsuspension is circulated through the IC loop at 200 mL/min. Bull's Eyemay allow cells that do not attach after the initial suspension andthose that may be left in the IC loop rather than in the bioreactor tobe re-suspended and transported to a different fiber within thebioreactor for subsequent attachment.

The Bull's Eye load may operate on the principle that a cell suspensionintroduced to the bioreactor via circulation of the IC loop may passthrough a different set of bioreactor fibers depending on the rate ofcirculation of that cell suspension in the IC loop.

Following an initial 200 mL/min suspension cycle in loading cells withuniform suspension (LCWUS), the cell suspension in the IC loop may becirculated alternately in the positive and negative directions atsequentially lower circulation rates: −100 mL/min, 50 mL/min, −25mL/min. Each progressively slower cycle of the IC loop may allow thosecells still left in suspension an additional opportunity to enter andattach to the inner surface of a bioreactor fiber.

Each cycling of the fluid in the IC loop may be followed by a 7-minutecell-attachment period during which the IC circulation rate may be zero.MSC cells have been demonstrated to attach within 5 minutes to the innersurface of a fiber in a bioreactor used in the QUANTUM cell expansionsystem. As such, the 7-minute attachment may allow for 5 minutes forcell attachment, and 2 extra minutes to allow for slower-attachingcells. The four total cycles of cell suspension and cell attachment inthe IC loop may be followed by a 24 hr attachment period after which anappropriate cell feeding schedule may be input as desired.

Day: −1 Coat Bioreactor

Purpose: coats the bioreactor membrane with a reagent.

Step 1: loads a reagent into the IC loop until the bag is empty.

Step 2: chases the reagent from the ARC into the IC loop.

Step 3: circulates the reagent in the IC loop.

Before starting this task, the following preconditions may be satisfied:

Include at least 40 mL of air in the cell inlet bag.

Table 10 describes the bags of solution that may be used to attach toeach line when performing Coat Bioreactor. These solutions andcorresponding volumes may be based on the default settings for thistask.

TABLE 10 Solutions for Coat Bioreactor Volume (estimation based onfactory default Bag Solution in Bag values) Cell Inlet None N/A ReagentFibronectin 5 mg Fibronectin in 100 mL PBS IC Media None N/A Wash PBS0.1 L + 6 mL/hr (overnight) EC Media None N/A

Coat Bioreactor Pathway: Task>System Management>Coat Bioreactor

Enter the values for each setting for step 1 shown in Table 11.

TABLE 11 Step 1 for Coat Bioreactor Laboratory Setting Factory DefaultDefault Modifications IC Inlet Reagent IC Inlet Rate 10 mL/min ICCirculation Rate 100 mL/min  EC Inlet None EC Inlet Rate  0 mL/min ECCirculation Rate 30 mL/min Outlet EC Outlet Rocker Control Stationary(0°) Stop Condition Empty Bag

Enter the values for each setting for step 2 shown in Table 12.

TABLE 12 Step 2 Setting for Coat Bioreactor Laboratory Setting FactoryDefault Default Modifications IC Inlet Wash IC Inlet Rate 10 mL/min ICCirculation Rate 100 mL/min  EC Inlet None EC Inlet Rate  0 mL/min ECCirculation Rate 30 mL/min Outlet EC Outlet Rocker Control Stationary(0°) Stop Condition IC Volume (22 mL)

Enter the values for each setting for step 3 shown in Table 13.

TABLE 13 Step 3 Settings for Coat Bioreactor Laboratory Setting FactoryDefault Default Modifications IC Inlet None IC Inlet Rate  0 mL/min ICCirculation Rate 20 mL/min EC Inlet Wash EC Inlet Rate 0.1 mL/min  ECCirculation Rate 30 mL/min Outlet EC Outlet Rocker Control Stationary(0°) Stop Condition Manual

Day: 0 IC EC Washout

Purpose: used to replace the fluid on both the IC circulation loop andthe EC circulation loop. The replacement volume is specified by thenumber of IC Volumes and EC Volumes exchanged. Table 14 describes thebags of solution that may be attached to each line when performing IC ECWashout. These solutions and corresponding volumes may be based on thedefault settings for this task.

TABLE 14 Solutions for IC EC Washout Volume (estimation based on factorydefault Bag Solution in Bag values) Cell Inlet None N/A Reagent None N/AIC Media Media with Protein 1.4 L Wash None N/A EC Media None N/A

IC EC Washout Pathway: Task>Washout>IC EC Washout

Confirm the values for each setting for IC EC Washout shown in Table 15.

TABLE 15 Task Settings for IC EC Washout Laboratory Setting FactoryDefault Default Modifications IC Inlet IC Media IC Inlet Rate 100 mL/minIC Circulation Rate −17 mL/min EC Inlet [EC Media] IC Media EC InletRate 148 mL/min EC Circulation Rate −1.7 mL/min Outlet IC and EC OutletRocker Control In Motion (−90°, 180°, 1 sec) Stop Condition Exchange(2.5 IC Volumes) (2.5 EC Volumes)

Day: 0 Condition Media

Follow the instructions in this task to allow the media to reachequilibrium with the provided gas supply before loading the cells. Thistask may include two separate steps:

Step 1: provides rapid contact between the media and the gas supply byusing a high EC circulation rate.

Step 2: maintains the system in a proper state until the operator isready to load the cells.

Table 16 describes the bags of solution that may be attached to eachline when performing Condition Media. These solutions and correspondingvolumes may be based on the default settings for this task.

TABLE 16 Solutions for Condition Media Volume (estimation based onfactory default Line Solution in Bag values) Cell Inlet None N/A ReagentNone N/A IC Media None N/A Wash None N/A EC Media Media without Protein0.1 L plus 6 mL/hour

Condition Media Pathway: Task>System Management>Condition Media

Enter the values for each setting for step 1 shown in Table 17.

TABLE 17 Step 1 Settings for Condition Media Laboratory Setting FactoryDefault Default Modifications IC Inlet None IC Inlet Rate  0 mL/min ICCirculation Rate 100 mL/min EC Inlet [EC Media] IC Media EC Inlet Rate 0.1 mL/min EC Circulation Rate 250 mL/min Outlet EC Outlet RockerControl Stationary (0°) Stop Condition Time (10 min)

Enter the values for each setting for step 2 shown in Table 18.

TABLE 18 Step 2 Settings for Condition Media Laboratory Setting FactoryDefault Default Modifications IC Inlet None IC Inlet Rate  0 mL/min ICCirculation Rate 100 mL/min EC Inlet [EC Media] IC Media EC Inlet Rate 0.1 mL/min EC Circulation Rate  30 mL/min Outlet EC Outlet RockerControl Stationary (0°) Stop Condition Manual

Day: 0 Load Cells with Uniform Suspension

Purpose: loads the cells into the bioreactor from the cell inlet baguntil the bag is empty. This task only uses IC circulation to distributethe cells and does not attempt to chase the cells from the line into thebioreactor. This task may include three separate steps.

Step 1: loads the cells from the cell inlet bag into the bioreactor.

Step 2: chases the cells from the ARC to the bioreactor. Larger chasevolumes spread the cells and move them towards the IC outlet.

Step 3: promotes distribution of cells across membrane via ICcirculation and no IC inlet thus no ultrafiltration.

Before starting this task, the following preconditions may be satisfied:

Include at least 40 mL of air in the cell inlet bag.

Table 19 describes the bags of solution that may be attached to eachline when performing Load Cells With Uniform Suspension. These solutionsand corresponding volumes may be based on the default settings for thistask.

TABLE 19 Solutions for Load Cells With Uniform Suspension Volume(estimation based on factory default Line Solution in Bag values) CellInlet Cells N/A Reagent None N/A IC Media Media with Protein 0.2 L WashNone N/A EC Media None N/A

Load Cells with Uniform Suspension Pathway: Task>Load and Attach>LoadCells with Uniform Suspension

Confirm the values for each setting for step 1 shown in Table 20.

TABLE 20 Step 1 Settings for Load Cells With Uniform SuspensionLaboratory Setting Factory Default Default Modifications IC Inlet CellIC Inlet Rate [50 mL/min]  25 mL/min IC Circulation Rate [200 mL/min]150 mL/min EC Inlet None EC Inlet Rate  0 mL/min EC Circulation Rate 30mL/min Outlet EC Outlet Rocker Control In Motion (−90°, 180°, 1 sec)Stop Condition Empty Bag

Confirm the values for each setting for step 2 shown in Table 21.

TABLE 21 Step 2 Settings for Load Cells with Uniform SuspensionLaboratory Setting Factory Default Default Modifications IC Inlet ICMedia IC Inlet Rate [50 mL/min]  25 mL/min IC Circulation Rate [200mL/min] 150 mL/min EC Inlet None EC Inlet Rate  0 mL/min EC CirculationRate 30 mL/min Outlet EC Outlet Rocker Control In Motion (−90°, 180°, 1sec) Stop Condition IC Volume (22 mL)

Confirm the values for each setting for step 3 shown in Table 22.

TABLE 22 Step 3 Settings for Load Cells with Uniform SuspensionLaboratory Setting Factory Default Default Modifications IC Inlet NoneIC Inlet Rate 0 mL/min IC Circulation Rate 200 mL/min  EC Inlet None ECInlet Rate 0 mL/min EC Circulation Rate 30 mL/min  Outlet EC OutletRocker Control In Motion (−90°, 180°, 1 sec) Stop Condition Time (2.0min)

Day: 0 Bull's Eye Attachment

Purpose: allows adherent cells to attach to the bioreactor membranewhile allowing flow on the EC circulation loop. The pump flow rate tothe IC loop may be set to zero.

Step 1: Allows cells 7 minutes to attach to the inner surface of thebioreactor at 180°.

Step 2: Circulates the IC fluid and the remaining suspended cells at ahigh rate in a direction opposite to the initial load.

Step 3: This step is a second 7.0 minute allowance for further cellattachment. Those cells that were relocated from the IC loop or from adifferent region of the bioreactor will be given a chance to settle andadhere to the bioreactor.

Step 4: Again re-circulates those cells remaining in the IC loop andthose cells that have yet to attach to a surface. Circulation may be inthe positive direction and the circulation rate may be lower this timeto avoid removing those cells that have already attached and to seedpreferentially regions of the bioreactor that may not have been seededin previous steps.

Step 5: This step is a third 7.0 minute allowance for further cellattachment. Those cells that were relocated from the IC loop or from adifferent region of the bioreactor will be given a chance to settle andadhere to the bioreactor.

Step 6: re-circulates those cells remaining in the IC loop and thosecells that have yet to attach to a surface. Circulation may be in thenegative direction and the circulation rate is lower this time to avoidremoving those cells that have already attached.

Step 7: 24 hour attach cells phase. Cells may have 24 hours to anchorsolidly to the bioreactor before feeding begins.

Table 23 describes the bags of solution that may be attached to eachline when performing Bull's Eye Attachment. These solutions andcorresponding volumes may be based on the default settings for thistask.

TABLE 23 Solutions for Bull's Eye Attachment Volume (estimation based onfactory default Bag Solution in Bag values) Cell Inlet None N/A ReagentNone N/A IC Media Media with Protein 6 mL/hour Wash None N/A EC MediaNone N/A

Bull's Eye Attachment Cells Pathway: Task>Custom>Custom

Enter the values for each setting shown in table 24.

TABLE 24 Step 1 Task Settings for Bull's Eve Attachment LaboratorySetting Factory Default Default Modifications IC Inlet None IC InletRate 0 mL/min IC Circulation Rate 0 mL/min EC Inlet [EC Media] EC InletRate 0.1 mL/min EC Circulation Rate 30 mL/min Outlet EC Outlet RockerControl [Stationary (0°)] Stationary (180°) Stop Condition Time (7.0min)

Enter the values for each setting shown in table 25.

TABLE 25 Step 2 Task Settings for Bull's Eye Attachment LaboratorySetting Factory Default Default Modifications IC Inlet None IC InletRate 0 mL/min IC Circulation Rate [0 mL/min] −100 mL/min EC Inlet NoneEC Inlet Rate 0 mL/min EC Circulation Rate 0 mL/min 30 mL/min Outlet ECOutlet Rocker Control [Stationary] In Motion (−90°, 180°, 1 sec) StopCondition [Manual] Time (2.0 min)

Enter the values for each setting shown in table 26

TABLE 26 Step 3 Task Settings for Bull's Eye Attachment LaboratorySetting Factory Default Default Modifications IC Inlet None IC InletRate 0 mL/min IC Circulation Rate 0 mL/min EC Inlet [EC Media] IC MediaEC Inlet Rate 0.1 mL/min EC Circulation Rate 30 mL/min Outlet EC OutletRocker Control Stationary (0°) Stop Condition Time (7.0 min)

Enter the values for each setting shown in table 27

TABLE 27 Step 4 Task Settings for Bull's Eye Attachment LaboratorySetting Factory Default Default Modifications IC Inlet None IC InletRate 0 mL/min IC Circulation Rate [0 mL/min] 50 mL/min EC Inlet None ECInlet Rate 0 mL/min EC Circulation Rate [0 mL/min] 30 mL/min Outlet ECOutlet Rocker Control [Stationary] In Motion (−90°, 180°, 1 sec) StopCondition [Manual] Time (4.0 min)

Enter the values for each setting shown in table 28.

TABLE 28 Step 5 Task Settings for Bull's Eye Attachment LaboratorySetting Factory Default Default Modifications IC Inlet None IC InletRate 0 mL/min IC Circulation Rate 0 mL/min EC Inlet [EC Media] EC InletRate 0.1 mL/min EC Circulation Rate 30 mL/min Outlet EC Outlet RockerControl Stationary (0°) Stop Condition Time (7.0 min)

Enter the values for each setting shown in table 29.

TABLE 29 Step 6 Task Settings for Bull's Eye Attachment LaboratorySetting Factory Default Default Modifications IC Inlet None IC InletRate 0 mL/min IC Circulation Rate [0 mL/min] −25 mL/min  EC Inlet NoneEC Inlet Rate 0 mL/min EC Circulation Rate 0 mL/min 30 mL/min Outlet ECOutlet Rocker Control [Stationary] In Motion (−90°, 180°, 1 sec) StopCondition [Manual] Time (8.0 min)

Enter the values for each setting shown in table 30.

TABLE 30 Task Settings for Bull's Eye Attachment Laboratory SettingFactory Default Default Modifications IC Inlet None IC Inlet Rate 0mL/min IC Circulation Rate 0 mL/min EC Inlet [EC Media] IC Media ECInlet Rate 0.1 mL/min EC Circulation Rate 30 mL/min Outlet EC OutletRocker Control Stationary (0°) Stop Condition [Manual] Time (1440.0 min)

Day: 1 Feed Cells

Purpose: continuously adds a low flow rate to the IC circulation loopand/or the EC circulation loop. There are several outlet settings thatcan be used to remove the fluid added to the system during this task.

Table 31 describes the bags of solution that may be attached to eachline when performing Feed Cells. These solutions and correspondingvolumes may be based on the default settings for this task.

TABLE 31 Solutions for Feed Cells Volume (estimation based Bag Solutionin Bag on factory default values) Cell Inlet None N/A Reagent None N/AIC Media Media with Protein 6 mL/hour Wash None N/A EC Media None N/AFeed Cells pathway: Task > Feed and Add > Feed Cells

Confirm the values for each setting for step 1 for shown in Table 32.

TABLE 32 Task Settings for Feed Cells Laboratory Setting Factory DefaultDefault Modifications IC Inlet IC Media IC Inlet Rate 0.1 mL/min ICCirculation Rate 20 mL/min EC Inlet None EC Inlet Rate 0 mL/min ECCirculation Rate 30 mL/min Outlet IC Outlet Rocker Control Stationary(0°) Stop Condition Manual

Increase IC Inlet rate as needed.

Release Adherent Cells and Harvest

Purpose: releases cells from the membrane, leaving the cells in the ICloop and transfers cells in suspension from the IC circulation loop,including cells in the bioreactor, into the harvest bag.

Step 1: performs the IC EC Washout task in preparation for adding areagent. For example, the system replaces IC EC media with PBS to removeprotein, Ca++, and Mg++ in preparation for adding trypsin.

Step 2: loads a reagent into the system until the bag is empty.

Step 3: chases the reagent into the IC loop.

Step 4: mixes the reagent within the IC loop.

Step 5: transfers cells in suspension from the IC circulation loop,including cells in the bioreactor, to the harvest bag.

Before starting this task, the following preconditions may be satisfied:

Include at least 40 mL of air on the cell inlet bag.

Table 33 describes the bags of solution that may be attached to eachline when performing Release Adherent Cells And Harvest. These solutionsand corresponding volumes may be based on the default settings for thistask.

TABLE 33 Solutions for Release Adherent Cells And Harvest Volume(estimation based Bag Solution in Bag on factory default values) CellInlet None N/A Reagent Trypsin 180 mL IC Media Media with Protein 0.6 LWash PBS 1.4 L EC Media None N/A

Release Adherent Cells Pathway: Task>Release and Harvest>ReleaseAdherent Cells and Harvest

Confirm the values for each setting for step 1 shown in Table 34.

TABLE 34 Step 1 Settings for Release Adherent Cells And HarvestLaboratory Setting Factory Default Default Modifications IC Inlet WashIC Inlet Rate 100 mL/mm IC Circulation Rate −17 mL/min EC Inlet Wash ECInlet Rate 148 mL/min EC Circulation Rate −1.7 mL/min Outlet IC and ECOutlet Rocker Control In Motion (−90°, 180°, 1 sec) Stop ConditionExchange (2.5 IC Volumes) (2.5 EC Volumes)

Confirm the values for each setting for step 2 shown in Table 35.

TABLE 35 Step 2 Settings for Release Adherent Cells And HarvestLaboratory Setting Factory Default Default Modifications IC InletReagent IC Inlet Rate 50 mL/min IC Circulation Rate 300 mL/min EC InletNone EC Inlet Rate 0 mL/min EC Circulation Rate 30 mL/min Outlet ECOutlet Rocker Control In Motion (−90°, 180°, 1 sec) Stop Condition EmptyBag

Confirm the values for each setting for step 3 shown in Table 36.

TABLE 36 Step 3 Settings for Release Adherent Cells And HarvestLaboratory Setting Factory Default Default Modifications IC Inlet WashIC Inlet Rate 50 mL/min IC Circulation Rate 300 mL/min EC Inlet None ECInlet Rate 0 mL/min EC Circulation Rate 30 mL/min Outlet EC OutletRocker Control In Motion (−90°, 180°, 1 sec) Stop Condition IC Volume(22 mL)

Confirm the values for each setting for step 4 shown in Table 37.

TABLE 37 Step 4 Settings for Release Adherent Cells And HarvestLaboratory Setting Factory Default Default Modifications IC Inlet NoneIC Inlet Rate 0 mL/min IC Circulation Rate 300 mL/min EC Inlet None ECInlet Rate 0 mL/min EC Circulation Rate 30 mL/min Outlet EC OutletRocker Control In Motion (−90°, 180°, 1 sec) Stop Condition Time (4 min)

Confirm the values for each setting for step 5 shown in Table 38.

TABLE 38 Step 5 Settings for Release Adherent Cells And HarvestLaboratory Setting Factory Default Default Modifications IC Inlet ICMedia IC Inlet Rate 400 mL/min IC Circulation Rate −70 mL/min EC Inlet[EC Media] IC Media EC Inlet Rate 60 mL/min EC Circulation Rate 30mL/min Outlet Harvest Rocker Control In Motion (−90°, 180°, 1 sec) StopCondition IC Volume (378 mL)

The results of the study may be as follows:

TABLE 39 Un- Mean 69% adjusted Flask Adjusted Doubling Doubling Time#Cells #Cells Agg Doubling Time Time Load (days) Loaded HarvestedViability (0-5) Time (Hrs) (Hrs) (Hrs) BullsEye 4.8 1.52E+06 1.97E+0898.1% 2 27.2 31.2 24.1 BullsEye 4.8 1.52E+06 2.05E+08 98.0% 2 26.8 30.724.1 BullsEye 4.8 1.52E+06 2.01E+08 99.3% 2 27.1 31.0 24.1 Control 4.81.52E+06 1.38E+08 99.3% 2 31.0 36.2 24.1

The Bull's Eye load may be evaluated using MSC from four differentdonors. Yields from Bull's Eye loaded harvests may be consistentlyhigher than the yields loaded using LCWUS and cultured under identicalconditions. The mean cell yield increase using Bull's Eye (n=6) vs.LCWUS (n=4) may be 25%.

Viability of MSC samples from the IC loop taken immediately afterperforming the Bull's Eye load may be 100%. Viability of MSC from Bull'sEye harvests may be over 98% for all samples. MSC from Bull's Eyeharvests may display typical morphology in culture, and all MSCbiomarkers measured by flow cytometry may conform to ISCT standards.

Example 3

The same protocol as described above with respect to Example 2 may beused to study modifications to the Bulls Eye attachment protocol. Themodifications to the Bulls Eye attachment (Bulls Eye II), and to theprotocol described above, include eliminating the attachments phasesafter the circulation rates: 100 ml/min; −50 ml/min; and 25 ml/min. Thatis, instead of having 7 minute stop conditions as described above, thereis no stop condition so that the next circulation rate follows theprevious circulation rate. A control, as well as an original Bulls Eyerun (Bulls Eye I) may also be performed as a comparison.

The results of this study may be as follows:

TABLE 40 Un- Mean 69% adjusted Flask Adjusted Doubling Doubling Time#Cells #Cells Agg Doubling Time Time Load (days) Loaded HarvestedViability (0-5) Time (Hrs) (Hrs) (Hrs) BullsEye I 4.9 1.52E+07 2.60E+0899.2% 0 25.4 28.7 26.0 (500 cells/cm2) Control 4.9 1.52E+07 1.94E+0897.5% 1 27.9 32.0 25.5 (345 cells/cm2) BullsEye II 4.9 1.52E+07 2.10E+0898.1% 1 27.2 31.1 ? BullsEye II 4.9 1.52E+07 2.07E+08 98.7% 1 27.3 31.2?

Various components may be referred to herein as “operably associated.”As used herein, “operably associated” refers to components that arelinked together in operable fashion, and encompasses embodiments inwhich components are linked directly, as well as embodiments in whichadditional components are placed between the two linked components.

The foregoing discussion of the one or more embodiments of the presentinvention has been presented for purposes of illustration anddescription. The foregoing is not intended to be limiting. In theforegoing Detailed Description for example, various features of the oneor more embodiments may have been grouped together for the purpose ofstreamlining the disclosure. This method of disclosure is not to beinterpreted as reflecting an intention that the embodiments require morefeatures than may be expressly recited in a claim. Rather, as thefollowing claims reflect, inventive aspects may lie in less than allfeatures of a single foregoing disclosed embodiment. Thus, the followingclaims are hereby incorporated into this Detailed Description, with eachclaim standing on its own as a separate embodiment of the presentinvention.

Moreover, though the description includes description of one or moreembodiments and certain variations and modifications, other variationsand modifications are within the scope of the invention (e.g., as may bewithin the skill and knowledge of those in the art, after understandingthe present disclosure). It is intended to obtain rights which includealternative embodiments to the extent permitted, including alternate,interchangeable and/or equivalent structures, functions, ranges or stepsto those claimed, whether or not such alternate, interchangeable and/orequivalent structures, functions, ranges or steps are disclosed herein,and without intending to publicly dedicate any patentable subjectmatter.

We claim:
 1. A method of growing cells in a cell expansion system, themethod comprising: circulating fluid, with a pump, through a bioreactorcomprising a hollow fiber membrane with a plurality of hollow fibers,wherein the fluid comprises a plurality of cells and the fluid entersthe bioreactor through a first inlet and exits the bioreactor through afirst outlet; reducing the rate of circulating fluid by reducing a flowrate of the pump; maintaining the bioreactor in a first horizontalorientation for a first predetermined period of time to allow at least afirst portion of the plurality of cells to settle and attach to a firstportion of at least one of the plurality of hollow fibers; after thefirst predetermined period of time, rotating, with a rotational device,the bioreactor to a second horizontal orientation that is about 180degrees from the first horizontal orientation; and after the rotating,expanding at least the first portion of the plurality of cells attachedto the first portion of the at least one of the plurality of hollowfibers while the bioreactor is oriented in the second horizontalorientation by feeding the portion of cells and growing the portion ofcells downward in the bioreactor under an influence of gravity toward aportion of the at least one of the plurality of hollow fibers that doesnot have attached cells.
 2. The method of claim 1, wherein the firstpredetermined period of time is long enough to allow the portion ofcells to attach and expand.
 3. The method of claim 2, wherein the firstpredetermined period of time is greater than about 10 hours.
 4. Themethod of claim 1, wherein the first predetermined period of time isless than about 8 minutes.
 5. The method of claim 4, wherein the firstpredetermined period of time is about 5 minutes.
 6. The method of claim1, further comprising: after the first predetermined period of time andbefore rotating the bioreactor to a second horizontal orientation:rotating the bioreactor to a first vertical orientation and maintainingthe bioreactor in the first vertical orientation for a secondpredetermined period of time; and after the second predetermined periodof time, rotating the bioreactor to a second vertical orientation thatis about 180 degrees from the first vertical orientation and maintainingthe bioreactor in the second vertical orientation for a thirdpredetermined period of time.
 7. The method of claim 6, wherein thesecond predetermined period of time is of sufficient duration to allowthe portion of cells to expand.
 8. The method of claim 7, wherein thethird predetermined period of time is equal in duration to the secondperiod of time.
 9. The method of claim 7, wherein the secondpredetermined period of time is at least about 10 hours.
 10. The methodof claim 1, wherein the plurality of cells comprises stem cells.
 11. Themethod of claim 10, wherein the stem cells comprise mesenchymal stemcells.
 12. The method of claim 1, wherein the plurality of cellscomprises one or more cells from the group consisting of: fibroblasts,keratinocytes, progenitor, endothelial, or combinations thereof.
 13. Themethod of claim 1, wherein the first portion comprises an inside surfaceof the at least one of the plurality of hollow fibers.
 14. The method ofclaim 13, wherein the second portion comprises a different portion ofthe inside surface of the at least one of the plurality of hollowfibers.
 15. The method of claim 1, wherein the first predeterminedperiod of time is long enough to allow the portion of cells to attach.